diff --git a/App/.idea/workspace.xml b/App/.idea/workspace.xml
index b943d44..336a0a3 100644
--- a/App/.idea/workspace.xml
+++ b/App/.idea/workspace.xml
@@ -1,11 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ChangeListManager">
-    <list default="true" id="ecb85847-acff-4336-b3d7-4f5563aac01d" name="Default" comment="">
-      <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/database/__init__.py" beforeDir="false" afterPath="$PROJECT_DIR$/database/__init__.py" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/db_script_pycharm.ddl" beforeDir="false" afterPath="$PROJECT_DIR$/db_script_pycharm.ddl" afterDir="false" />
-    </list>
+    <list default="true" id="ecb85847-acff-4336-b3d7-4f5563aac01d" name="Default" comment="" />
     <option name="EXCLUDED_CONVERTED_TO_IGNORED" value="true" />
     <option name="TRACKING_ENABLED" value="true" />
     <option name="SHOW_DIALOG" value="false" />
@@ -84,27 +80,36 @@
   </component>
   <component name="FileEditorManager">
     <leaf SIDE_TABS_SIZE_LIMIT_KEY="300">
-      <file leaf-file-name="application.py" pinned="false" current-in-tab="false">
+      <file leaf-file-name="application.py" pinned="false" current-in-tab="true">
         <entry file="file://$PROJECT_DIR$/application.py">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="102">
-              <caret line="7" selection-start-line="7" selection-end-line="7" />
+            <state relative-caret-position="51">
+              <caret line="3" column="48" lean-forward="true" selection-start-line="3" selection-start-column="48" selection-end-line="3" selection-end-column="48" />
             </state>
           </provider>
         </entry>
       </file>
-      <file leaf-file-name="__init__.py" pinned="false" current-in-tab="true">
+      <file leaf-file-name="__init__.py" pinned="false" current-in-tab="false">
         <entry file="file://$PROJECT_DIR$/database/__init__.py">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="643">
-              <caret line="156" column="4" selection-start-line="156" selection-start-column="4" selection-end-line="156" selection-end-column="4" />
+            <state relative-caret-position="5763">
+              <caret line="339" column="44" lean-forward="true" selection-start-line="339" selection-start-column="44" selection-end-line="339" selection-end-column="44" />
               <folding>
-                <element signature="e#0#37#0" expanded="true" />
+                <element signature="e#0#11#0" expanded="true" />
               </folding>
             </state>
           </provider>
         </entry>
       </file>
+      <file leaf-file-name="db_script_pycharm.ddl" pinned="false" current-in-tab="false">
+        <entry file="file://$PROJECT_DIR$/db_script_pycharm.ddl">
+          <provider selected="true" editor-type-id="text-editor">
+            <state relative-caret-position="102">
+              <caret line="6" column="70" selection-start-line="6" selection-start-column="70" selection-end-line="6" selection-end-column="70" />
+            </state>
+          </provider>
+        </entry>
+      </file>
     </leaf>
   </component>
   <component name="FileTemplateManagerImpl">
@@ -115,6 +120,11 @@
       </list>
     </option>
   </component>
+  <component name="FindInProjectRecents">
+    <findStrings>
+      <find>duration</find>
+    </findStrings>
+  </component>
   <component name="Git.Settings">
     <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$/.." />
   </component>
@@ -126,6 +136,7 @@
         <option value="$PROJECT_DIR$/upgrader/__init__.py" />
         <option value="$PROJECT_DIR$/commands/__init__.py" />
         <option value="$PROJECT_DIR$/application.py" />
+        <option value="$PROJECT_DIR$/db_script_pycharm.ddl" />
         <option value="$PROJECT_DIR$/database/__init__.py" />
       </list>
     </option>
@@ -257,7 +268,21 @@
       <option name="project" value="LOCAL" />
       <updated>1529522603097</updated>
     </task>
-    <option name="localTasksCounter" value="5" />
+    <task id="LOCAL-00005" summary="Completed UPDATE operations &amp; updated CQL file">
+      <created>1529747881468</created>
+      <option name="number" value="00005" />
+      <option name="presentableId" value="LOCAL-00005" />
+      <option name="project" value="LOCAL" />
+      <updated>1529747881468</updated>
+    </task>
+    <task id="LOCAL-00006" summary="Finished creation of methods for working with CQL">
+      <created>1529752871693</created>
+      <option name="number" value="00006" />
+      <option name="presentableId" value="LOCAL-00006" />
+      <option name="project" value="LOCAL" />
+      <updated>1529752871693</updated>
+    </task>
+    <option name="localTasksCounter" value="7" />
     <servers />
   </component>
   <component name="ToolWindowManager">
@@ -265,14 +290,14 @@
     <editor active="true" />
     <layout>
       <window_info anchor="bottom" id="TODO" order="12" />
-      <window_info anchor="bottom" id="Event Log" order="3" side_tool="true" />
+      <window_info anchor="bottom" id="Event Log" order="3" side_tool="true" weight="0.32965517" />
       <window_info anchor="bottom" id="Database Changes" order="2" show_stripe_button="false" />
       <window_info anchor="bottom" id="Version Control" order="1" />
       <window_info anchor="bottom" id="Python Console" order="5" />
       <window_info anchor="bottom" id="Run" order="8" weight="0.32965517" />
       <window_info anchor="bottom" id="Terminal" order="4" />
       <window_info anchor="right" id="Remote Host" order="2" />
-      <window_info active="true" content_ui="combo" id="Project" order="1" visible="true" weight="0.234375" />
+      <window_info content_ui="combo" id="Project" order="1" visible="true" weight="0.234375" />
       <window_info anchor="bottom" id="Docker" order="0" show_stripe_button="false" />
       <window_info anchor="right" id="Database" order="0" />
       <window_info anchor="right" id="SciView" order="1" />
@@ -299,7 +324,9 @@
     <MESSAGE value="Packages and cPrint method - pip upgrader also included" />
     <MESSAGE value="Created class for database managing - files for database creation adapted to Cassandra model" />
     <MESSAGE value="Updated database model and added methods for &quot;InsertOperations&quot;" />
-    <option name="LAST_COMMIT_MESSAGE" value="Updated database model and added methods for &quot;InsertOperations&quot;" />
+    <MESSAGE value="Completed UPDATE operations &amp; updated CQL file" />
+    <MESSAGE value="Finished creation of methods for working with CQL" />
+    <option name="LAST_COMMIT_MESSAGE" value="Finished creation of methods for working with CQL" />
   </component>
   <component name="XDebuggerManager">
     <breakpoint-manager>
@@ -319,7 +346,7 @@
         <state relative-caret-position="1581">
           <caret line="94" column="62" selection-start-line="94" selection-start-column="62" selection-end-line="94" selection-end-column="62" />
           <folding>
-            <element signature="e#0#37#0" expanded="true" />
+            <element signature="e#0#11#0" expanded="true" />
           </folding>
         </state>
       </provider>
@@ -336,7 +363,7 @@
         <state relative-caret-position="1581">
           <caret line="94" column="8" selection-start-line="94" selection-start-column="8" selection-end-line="94" selection-end-column="8" />
           <folding>
-            <element signature="e#0#37#0" expanded="true" />
+            <element signature="e#0#11#0" expanded="true" />
           </folding>
         </state>
       </provider>
@@ -353,7 +380,7 @@
         <state relative-caret-position="1428">
           <caret line="84" lean-forward="true" selection-start-line="84" selection-end-line="84" />
           <folding>
-            <element signature="e#0#37#0" expanded="true" />
+            <element signature="e#0#11#0" expanded="true" />
           </folding>
         </state>
       </provider>
@@ -370,7 +397,7 @@
         <state relative-caret-position="1054">
           <caret line="62" column="41" selection-start-line="62" selection-start-column="41" selection-end-line="62" selection-end-column="41" />
           <folding>
-            <element signature="e#0#37#0" expanded="true" />
+            <element signature="e#0#11#0" expanded="true" />
           </folding>
         </state>
       </provider>
@@ -426,13 +453,6 @@
       </provider>
     </entry>
     <entry file="file://$PROJECT_DIR$/app_data.dict" />
-    <entry file="file://$PROJECT_DIR$/application.py">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="102">
-          <caret line="7" selection-start-line="7" selection-end-line="7" />
-        </state>
-      </provider>
-    </entry>
     <entry file="file://$USER_HOME$/.PyCharm2018.1/system/python_stubs/-272786505/builtins.py">
       <provider selected="true" editor-type-id="text-editor">
         <state relative-caret-position="233">
@@ -441,17 +461,28 @@
       </provider>
     </entry>
     <entry file="file://$PROJECT_DIR$/db_script_pycharm.ddl">
-      <provider selected="true" editor-type-id="text-editor" />
+      <provider selected="true" editor-type-id="text-editor">
+        <state relative-caret-position="102">
+          <caret line="6" column="70" selection-start-line="6" selection-start-column="70" selection-end-line="6" selection-end-column="70" />
+        </state>
+      </provider>
     </entry>
     <entry file="file://$PROJECT_DIR$/database/__init__.py">
       <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="643">
-          <caret line="156" column="4" selection-start-line="156" selection-start-column="4" selection-end-line="156" selection-end-column="4" />
+        <state relative-caret-position="5763">
+          <caret line="339" column="44" lean-forward="true" selection-start-line="339" selection-start-column="44" selection-end-line="339" selection-end-column="44" />
           <folding>
-            <element signature="e#0#37#0" expanded="true" />
+            <element signature="e#0#11#0" expanded="true" />
           </folding>
         </state>
       </provider>
     </entry>
+    <entry file="file://$PROJECT_DIR$/application.py">
+      <provider selected="true" editor-type-id="text-editor">
+        <state relative-caret-position="51">
+          <caret line="3" column="48" lean-forward="true" selection-start-line="3" selection-start-column="48" selection-end-line="3" selection-end-column="48" />
+        </state>
+      </provider>
+    </entry>
   </component>
 </project>
\ No newline at end of file
diff --git a/Design/DB_STRUCTURE/Logical.svg b/Design/DB_STRUCTURE/Logical.svg
index e281edf..8174878 100644
--- a/Design/DB_STRUCTURE/Logical.svg
+++ b/Design/DB_STRUCTURE/Logical.svg
@@ -137,58 +137,37 @@ Playlist
 P
 </text>
 <text x="26" y="32" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-playlist_id
+playlist_unique_id
 </text>
 <text x="16" y="46" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-o
+*
 </text>
 <text x="26" y="46" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-number_elements
+playlist_id
 </text>
 <text x="16" y="60" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
 o
 </text>
 <text x="26" y="60" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-times_requested
+number_elements
 </text>
 <text x="16" y="74" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
 o
 </text>
 <text x="26" y="74" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-playlist_quality
+times_requested
 </text>
 <text x="16" y="88" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
 o
 </text>
 <text x="26" y="88" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-playlist_format
-</text>
-</g>
-<g  fill="rgb(164,225,255)" stroke="rgb(0,0,255)" fill-opacity="1.0" stroke-opacity="1.0" clip-path="url(#clipPath6_0_)" transform="translate(302,31)" >
-<rect x="0" y="0" width="169" height="109" rx="20" ry="20" />
-<text id="User" x="73" y="14" fill="rgb(0,0,255)" font-weight="bold"  fill-opacity="1.0" font-size="10" stroke="none">
-User
-</text>
-<text x="16" y="32" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-*
-</text>
-<text x="2" y="32" fill="rgb(0,0,255)" fill-opacity="1.0" font-size="10" stroke="none">
-P
-</text>
-<text x="26" y="32" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-user_id
-</text>
-<text x="16" y="46" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-o
-</text>
-<text x="26" y="46" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-username
+playlist_quality
 </text>
-<text x="16" y="60" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+<text x="16" y="102" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
 o
 </text>
-<text x="26" y="60" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-name
+<text x="26" y="102" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+playlist_format
 </text>
 </g>
 <g  fill="rgb(164,225,255)" stroke="rgb(0,0,255)" fill-opacity="1.0" stroke-opacity="1.0" clip-path="url(#clipPath5_0_)" transform="translate(39,29)" >
@@ -260,5 +239,38 @@ o
 is_metadata_by_user
 </text>
 </g>
+<g  fill="rgb(164,225,255)" stroke="rgb(0,0,255)" fill-opacity="1.0" stroke-opacity="1.0" clip-path="url(#clipPath6_0_)" transform="translate(302,31)" >
+<rect x="0" y="0" width="169" height="109" rx="20" ry="20" />
+<text id="User" x="73" y="14" fill="rgb(0,0,255)" font-weight="bold"  fill-opacity="1.0" font-size="10" stroke="none">
+User
+</text>
+<text x="16" y="32" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+*
+</text>
+<text x="2" y="32" fill="rgb(0,0,255)" fill-opacity="1.0" font-size="10" stroke="none">
+P
+</text>
+<text x="26" y="32" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+user_id
+</text>
+<text x="16" y="46" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+o
+</text>
+<text x="26" y="46" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+username
+</text>
+<text x="16" y="60" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+o
+</text>
+<text x="26" y="60" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+name
+</text>
+<text x="16" y="74" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+o
+</text>
+<text x="26" y="74" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+first_use
+</text>
+</g>
 
 </svg>
\ No newline at end of file
diff --git a/Design/DB_STRUCTURE/Relational.svg b/Design/DB_STRUCTURE/Relational.svg
index b7631e2..b073c52 100644
--- a/Design/DB_STRUCTURE/Relational.svg
+++ b/Design/DB_STRUCTURE/Relational.svg
@@ -23,7 +23,7 @@
 </g>
 </svg>
 <clipPath clipPathUnits="userSpaceOnUse" id="clipPath4_0_">
-<rect x="0" y="0" width="253" height="110" />
+<rect x="0" y="0" width="253" height="140" />
 </clipPath>
 <clipPath clipPathUnits="userSpaceOnUse" id="clipPath7_0_">
 <rect x="0" y="0" width="235" height="127" />
@@ -80,7 +80,7 @@
 <polygon stroke="rgb(0,0,0)" stroke-dasharray="none" points="794 467 800 464 800 470" fill="rgb(0,0,0)" stroke-width="1" stroke-opacity="1.0"  />
 </g>
 <g  fill="rgb(255,255,180)" stroke="rgb(0,0,255)" fill-opacity="1.0" stroke-opacity="1.0" clip-path="url(#clipPath4_0_)" transform="translate(4,390)" >
-<rect x="0" y="0" width="252" height="109" />
+<rect x="0" y="0" width="252" height="139" />
 <text id="Playlist" x="108" y="14" fill="rgb(0,0,255)" font-weight="bold"  fill-opacity="1.0" font-size="10" stroke="none">
 Playlist
 </text>
@@ -92,33 +92,60 @@ Playlist
 P
 </text>
 <text x="26" y="32" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-playlist_id
+playlist_unique_id
 </text>
-<text x="131" y="32" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
+<text x="133" y="32" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
 VARCHAR2 (256 CHAR)
 </text>
 <text x="16" y="46" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-
+*
 </text>
 <text x="26" y="46" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-number_elements
+playlist_id
 </text>
-<text x="131" y="46" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
-INTEGER
+<text x="133" y="46" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
+VARCHAR2 (256 CHAR)
 </text>
 <text x="16" y="60" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
 
 </text>
 <text x="26" y="60" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+number_elements
+</text>
+<text x="133" y="60" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
+INTEGER
+</text>
+<text x="16" y="74" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+
+</text>
+<text x="26" y="74" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
 times_requested
 </text>
-<text x="131" y="60" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
+<text x="133" y="74" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
+INTEGER
+</text>
+<text x="16" y="88" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+
+</text>
+<text x="26" y="88" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+playlist_quality
+</text>
+<text x="133" y="88" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
 INTEGER
 </text>
-<line x1="0" y1="66" x2="251" y2="66" fill="none" stroke="rgb(0,0,255)"/>
-<use xlink:href="#pk_sym" x="4" y="73" width="8" height="8" fill-opacity="1.0"/>
-<text x="16" y="80" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-Playlist_PK (playlist_id)
+<text x="16" y="102" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+
+</text>
+<text x="26" y="102" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+playlist_format
+</text>
+<text x="133" y="102" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
+INTEGER
+</text>
+<line x1="0" y1="108" x2="251" y2="108" fill="none" stroke="rgb(0,0,255)"/>
+<use xlink:href="#pk_sym" x="4" y="115" width="8" height="8" fill-opacity="1.0"/>
+<text x="16" y="122" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+Playlist_PK (playlist_unique_id)
 </text>
 </g>
 <g  fill="rgb(255,255,180)" stroke="rgb(0,0,255)" fill-opacity="1.0" stroke-opacity="1.0" clip-path="url(#clipPath7_0_)" transform="translate(284,402)" >
@@ -194,7 +221,7 @@ P
 <text x="26" y="32" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
 user_id
 </text>
-<text x="92" y="32" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
+<text x="84" y="32" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
 INTEGER
 </text>
 <text x="16" y="46" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
@@ -203,7 +230,7 @@ INTEGER
 <text x="26" y="46" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
 username
 </text>
-<text x="92" y="46" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
+<text x="84" y="46" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
 VARCHAR2 (45 CHAR)
 </text>
 <text x="16" y="60" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
@@ -212,12 +239,21 @@ VARCHAR2 (45 CHAR)
 <text x="26" y="60" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
 name
 </text>
-<text x="92" y="60" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
+<text x="84" y="60" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
 CLOB
 </text>
-<line x1="0" y1="66" x2="202" y2="66" fill="none" stroke="rgb(0,0,255)"/>
-<use xlink:href="#pk_sym" x="4" y="73" width="8" height="8" fill-opacity="1.0"/>
-<text x="16" y="80" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+<text x="16" y="74" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+
+</text>
+<text x="26" y="74" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+first_use
+</text>
+<text x="84" y="74" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
+DATE
+</text>
+<line x1="0" y1="80" x2="202" y2="80" fill="none" stroke="rgb(0,0,255)"/>
+<use xlink:href="#pk_sym" x="4" y="87" width="8" height="8" fill-opacity="1.0"/>
+<text x="16" y="94" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
 User_PK (user_id)
 </text>
 </g>
@@ -303,9 +339,9 @@ Playlist_has_Music
 PF
 </text>
 <text x="26" y="32" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-Playlist_playlist_id
+playlist_unique_id
 </text>
-<text x="134" y="32" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
+<text x="133" y="32" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
 VARCHAR2 (256 CHAR)
 </text>
 <text x="16" y="46" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
@@ -317,39 +353,21 @@ PF
 <text x="26" y="46" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
 Music_file_id
 </text>
-<text x="134" y="46" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
+<text x="133" y="46" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
 VARCHAR2 (256 CHAR)
 </text>
-<text x="16" y="60" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-
-</text>
-<text x="26" y="60" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-playlist_quality
-</text>
-<text x="134" y="60" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
-INTEGER
-</text>
-<text x="16" y="74" fill="rgb(255,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-
-</text>
-<text x="26" y="74" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-playlist_format
-</text>
-<text x="134" y="74" fill="rgb(0,128,0)" fill-opacity="1.0" font-size="10" stroke="none">
-INTEGER
-</text>
-<line x1="0" y1="80" x2="304" y2="80" fill="none" stroke="rgb(0,0,255)"/>
-<use xlink:href="#pk_sym" x="4" y="87" width="8" height="8" fill-opacity="1.0"/>
-<text x="16" y="94" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-Playlist_has_Music_PK (Playlist_playlist_id, Music_file_id)
+<line x1="0" y1="52" x2="304" y2="52" fill="none" stroke="rgb(0,0,255)"/>
+<use xlink:href="#pk_sym" x="4" y="59" width="8" height="8" fill-opacity="1.0"/>
+<text x="16" y="66" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+Playlist_has_Music_PK (Music_file_id, playlist_unique_id)
 </text>
-<line x1="0" y1="100" x2="304" y2="100" fill="none" stroke="rgb(0,0,255)"/>
-<use xlink:href="#fk_sym" x="4" y="107" width="8" height="8" fill-opacity="1.0"/><a xlink:href="#Playlist" >
-<text x="16" y="114" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
-Playlist_has_Music_Playlist_FK (Playlist_playlist_id)
+<line x1="0" y1="72" x2="304" y2="72" fill="none" stroke="rgb(0,0,255)"/>
+<use xlink:href="#fk_sym" x="4" y="79" width="8" height="8" fill-opacity="1.0"/><a xlink:href="#Playlist" >
+<text x="16" y="86" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+Playlist_has_Music_Playlist_FK (playlist_unique_id)
 </text></a>
-<use xlink:href="#fk_sym" x="4" y="121" width="8" height="8" fill-opacity="1.0"/><a xlink:href="#Music" >
-<text x="16" y="128" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
+<use xlink:href="#fk_sym" x="4" y="93" width="8" height="8" fill-opacity="1.0"/><a xlink:href="#Music" >
+<text x="16" y="100" fill="rgb(0,0,0)" fill-opacity="1.0" font-size="10" stroke="none">
 Playlist_has_Music_Music_FK (Music_file_id)
 </text></a>
 </g>
diff --git a/Design/DB_STRUCTURE/database_design/datatypes/Diagrams.local b/Design/DB_STRUCTURE/database_design/datatypes/Diagrams.local
index 40ff85f..c1f552c 100644
--- a/Design/DB_STRUCTURE/database_design/datatypes/Diagrams.local
+++ b/Design/DB_STRUCTURE/database_design/datatypes/Diagrams.local
@@ -1,4 +1,4 @@
 <?xml version = '1.0' encoding = 'UTF-8'?>
 <oracle.dbtools.crest.model.design.datatypes.DataTypesDesign>
-   <object objectType="main_view" objectID="CFDE5FC8-D6A4-DF2D-FAA9-F1FC327377FA" name="" visible="false"/>
+   <object objectType="main_view" objectID="CFDE5FC8-D6A4-DF2D-FAA9-F1FC327377FA" name="DataTypes" visible="false"/>
 </oracle.dbtools.crest.model.design.datatypes.DataTypesDesign>
diff --git a/Design/DB_STRUCTURE/database_design/logical/Objects.local b/Design/DB_STRUCTURE/database_design/logical/Objects.local
index 59937eb..da73ab3 100644
--- a/Design/DB_STRUCTURE/database_design/logical/Objects.local
+++ b/Design/DB_STRUCTURE/database_design/logical/Objects.local
@@ -1,14 +1,14 @@
 <?xml version = '1.0' encoding = 'UTF-8'?>
 <oracle.dbtools.crest.model.design.logical.LogicalDesign>
    <object objectType="Entity" objectID="1558C95F-4CEC-1E30-AA15-58B7C6ACD81B" name="Metadata" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Entity" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="" propertyTargetId=""/>
-   <object objectType="Entity" objectID="312E0255-FAA7-1630-54E5-A4FCB50F6276" name="Preferences" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Entity" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="" propertyTargetId=""/>
+   <object objectType="Entity" objectID="FB782D70-50E0-0A98-4654-5E94050F8458" name="Music" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Entity" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="" propertyTargetId=""/>
    <object objectType="Entity" objectID="52FEBBBF-C76E-AEF4-45C5-3341E59BD946" name="Playlist" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Entity" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="" propertyTargetId=""/>
-   <object objectType="Entity" objectID="96125017-F1D2-153D-CBAC-D12E0939CF4E" name="User" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Entity" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="" propertyTargetId=""/>
+   <object objectType="Entity" objectID="312E0255-FAA7-1630-54E5-A4FCB50F6276" name="Preferences" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Entity" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="" propertyTargetId=""/>
    <object objectType="Entity" objectID="B1A287E6-50CA-DB8B-0AAD-60C303A2A402" name="Statistics" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Entity" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="" propertyTargetId=""/>
-   <object objectType="Entity" objectID="FB782D70-50E0-0A98-4654-5E94050F8458" name="Music" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Entity" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="" propertyTargetId=""/>
-   <object objectType="Relation" objectID="1D1B52B1-8974-5046-5AB7-7AB4BF89C08A" name="Playlist_has_Music" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Relation" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="52FEBBBF-C76E-AEF4-45C5-3341E59BD946" propertyTargetId="FB782D70-50E0-0A98-4654-5E94050F8458"/>
-   <object objectType="Relation" objectID="46906DFA-66DD-2DD5-790C-7A87FFE7755C" name="has" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Relation" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="FB782D70-50E0-0A98-4654-5E94050F8458" propertyTargetId="1558C95F-4CEC-1E30-AA15-58B7C6ACD81B"/>
+   <object objectType="Entity" objectID="96125017-F1D2-153D-CBAC-D12E0939CF4E" name="User" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Entity" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="" propertyTargetId=""/>
    <object objectType="Relation" objectID="B934A368-41CA-2247-7505-4DDD707ADAB7" name="creates" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Relation" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="96125017-F1D2-153D-CBAC-D12E0939CF4E" propertyTargetId="B1A287E6-50CA-DB8B-0AAD-60C303A2A402"/>
-   <object objectType="Relation" objectID="C49FD692-24A0-3030-2280-A4D5B8CDFC01" name="sets" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Relation" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="96125017-F1D2-153D-CBAC-D12E0939CF4E" propertyTargetId="312E0255-FAA7-1630-54E5-A4FCB50F6276"/>
+   <object objectType="Relation" objectID="46906DFA-66DD-2DD5-790C-7A87FFE7755C" name="has" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Relation" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="FB782D70-50E0-0A98-4654-5E94050F8458" propertyTargetId="1558C95F-4CEC-1E30-AA15-58B7C6ACD81B"/>
    <object objectType="Relation" objectID="DDBAFE8B-B820-1773-EE96-8B363262CAA9" name="History" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Relation" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="96125017-F1D2-153D-CBAC-D12E0939CF4E" propertyTargetId="FB782D70-50E0-0A98-4654-5E94050F8458"/>
+   <object objectType="Relation" objectID="1D1B52B1-8974-5046-5AB7-7AB4BF89C08A" name="Playlist_has_Music" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Relation" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="52FEBBBF-C76E-AEF4-45C5-3341E59BD946" propertyTargetId="FB782D70-50E0-0A98-4654-5E94050F8458"/>
+   <object objectType="Relation" objectID="C49FD692-24A0-3030-2280-A4D5B8CDFC01" name="sets" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.logical.Relation" propertyParentId="6F505A55-3C56-E65E-61AB-E3E34318876E" propertySourceId="96125017-F1D2-153D-CBAC-D12E0939CF4E" propertyTargetId="312E0255-FAA7-1630-54E5-A4FCB50F6276"/>
 </oracle.dbtools.crest.model.design.logical.LogicalDesign>
diff --git a/Design/DB_STRUCTURE/database_design/logical/entity/seg_0/52FEBBBF-C76E-AEF4-45C5-3341E59BD946.xml b/Design/DB_STRUCTURE/database_design/logical/entity/seg_0/52FEBBBF-C76E-AEF4-45C5-3341E59BD946.xml
index 34edc97..7392b41 100644
--- a/Design/DB_STRUCTURE/database_design/logical/entity/seg_0/52FEBBBF-C76E-AEF4-45C5-3341E59BD946.xml
+++ b/Design/DB_STRUCTURE/database_design/logical/entity/seg_0/52FEBBBF-C76E-AEF4-45C5-3341E59BD946.xml
@@ -15,6 +15,19 @@
 <minVolumes>0</minVolumes>
 <normalForm>Third</normalForm>
 <attributes itemClass="oracle.dbtools.crest.model.design.logical.Attribute">
+<Attribute name="playlist_unique_id" id="ADCC2E08-E4C7-1BEB-5C48-EFD99B682848">
+<createdBy>Javier Alonso Silva</createdBy>
+<createdTime>2018-06-23 10:18:07 UTC</createdTime>
+<ownerDesignName>database_design</ownerDesignName>
+<engineerTo>
+<item key="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" value="true"/>
+</engineerTo>
+<useDomainConstraints>false</useDomainConstraints>
+<use>1</use>
+<logicalDatatype>LOGDT024</logicalDatatype>
+<dataTypeSize>256 CHAR</dataTypeSize>
+<ownDataTypeParameters>256 CHAR,,</ownDataTypeParameters>
+</Attribute>
 <Attribute name="playlist_id" id="16C788DC-D5DE-47B4-78C1-EA4DE822865E">
 <createdBy>Javier Alonso Silva</createdBy>
 <createdTime>2018-06-18 14:37:39 UTC</createdTime>
@@ -92,7 +105,7 @@
 </engineerTo>
 <pk>true</pk>
 <usedAttributes>
-<attributeRef>16C788DC-D5DE-47B4-78C1-EA4DE822865E</attributeRef>
+<attributeRef>ADCC2E08-E4C7-1BEB-5C48-EFD99B682848</attributeRef>
 </usedAttributes>
 </identifier>
 </identifiers>
diff --git a/Design/DB_STRUCTURE/database_design/logical/entity/seg_0/96125017-F1D2-153D-CBAC-D12E0939CF4E.xml b/Design/DB_STRUCTURE/database_design/logical/entity/seg_0/96125017-F1D2-153D-CBAC-D12E0939CF4E.xml
index bd61c26..8558eb3 100644
--- a/Design/DB_STRUCTURE/database_design/logical/entity/seg_0/96125017-F1D2-153D-CBAC-D12E0939CF4E.xml
+++ b/Design/DB_STRUCTURE/database_design/logical/entity/seg_0/96125017-F1D2-153D-CBAC-D12E0939CF4E.xml
@@ -54,6 +54,19 @@
 <logicalDatatype>LOGDT040</logicalDatatype>
 <ownDataTypeParameters>,,</ownDataTypeParameters>
 </Attribute>
+<Attribute name="first_use" id="E0AB3B5D-AAD7-7982-722B-F8C33F15B736">
+<createdBy>Javier Alonso Silva</createdBy>
+<createdTime>2018-06-23 11:11:47 UTC</createdTime>
+<ownerDesignName>database_design</ownerDesignName>
+<engineerTo>
+<item key="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" value="true"/>
+</engineerTo>
+<nullsAllowed>true</nullsAllowed>
+<useDomainConstraints>false</useDomainConstraints>
+<use>1</use>
+<logicalDatatype>LOGDT008</logicalDatatype>
+<ownDataTypeParameters>,,</ownDataTypeParameters>
+</Attribute>
 </attributes>
 <identifiers itemClass="oracle.dbtools.crest.model.design.logical.CandidateKey">
 <identifier id="3E09607E-650C-5E05-C7AC-0E839F482CA2" name="User PK">
diff --git a/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/Objects.local b/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/Objects.local
index 1e510fa..afb34a8 100644
--- a/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/Objects.local
+++ b/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/Objects.local
@@ -1,18 +1,18 @@
 <?xml version = '1.0' encoding = 'UTF-8'?>
 <oracle.dbtools.crest.model.design.relational.RelationalDesign>
-   <object objectType="Table" objectID="0AF231FE-3CA2-BFD0-E42B-0DFDC72D4D26" name="Playlist" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.Table" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="" propertyTargetId=""/>
-   <object objectType="Table" objectID="1243C675-86A2-977F-2EFA-8F6C72D2CB26" name="Statistics" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.Table" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="" propertyTargetId=""/>
-   <object objectType="Table" objectID="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" name="User" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.Table" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="" propertyTargetId=""/>
+   <object objectType="Table" objectID="F0AD5A40-5659-C806-BEA1-595FD0DB5F39" name="History" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.Table" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="" propertyTargetId=""/>
+   <object objectType="Table" objectID="D1128F38-5763-FC3D-4FB1-14F78EDBE4CB" name="Metadata" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.Table" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="" propertyTargetId=""/>
    <object objectType="Table" objectID="25DE0936-5106-79A2-1678-9EAA1E0DA843" name="Music" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.Table" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="" propertyTargetId=""/>
+   <object objectType="Table" objectID="0AF231FE-3CA2-BFD0-E42B-0DFDC72D4D26" name="Playlist" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.Table" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="" propertyTargetId=""/>
    <object objectType="Table" objectID="47A181FD-9D20-6987-2EAE-0B7F53C88FB3" name="Playlist_has_Music" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.Table" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="" propertyTargetId=""/>
    <object objectType="Table" objectID="D088A558-CA22-9A96-F938-4F7712E4AEF1" name="Preferences" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.Table" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="" propertyTargetId=""/>
-   <object objectType="Table" objectID="D1128F38-5763-FC3D-4FB1-14F78EDBE4CB" name="Metadata" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.Table" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="" propertyTargetId=""/>
-   <object objectType="Table" objectID="F0AD5A40-5659-C806-BEA1-595FD0DB5F39" name="History" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.Table" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="" propertyTargetId=""/>
-   <object objectType="FKIndexAssociation" objectID="14761BF2-0284-F09E-1C36-5AD59C18B84E" name="History_Music_FK" containerID="F0AD5A40-5659-C806-BEA1-595FD0DB5F39" refContainerID="25DE0936-5106-79A2-1678-9EAA1E0DA843" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="25DE0936-5106-79A2-1678-9EAA1E0DA843" propertyTargetId="F0AD5A40-5659-C806-BEA1-595FD0DB5F39"/>
-   <object objectType="FKIndexAssociation" objectID="518E00B2-30C8-083A-0841-D61034BE188E" name="Playlist_has_Music_Playlist_FK" containerID="47A181FD-9D20-6987-2EAE-0B7F53C88FB3" refContainerID="0AF231FE-3CA2-BFD0-E42B-0DFDC72D4D26" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="0AF231FE-3CA2-BFD0-E42B-0DFDC72D4D26" propertyTargetId="47A181FD-9D20-6987-2EAE-0B7F53C88FB3"/>
-   <object objectType="FKIndexAssociation" objectID="51EE3780-3B5D-E1A1-65B0-7ED699DD5948" name="Statistics_User_FK" containerID="1243C675-86A2-977F-2EFA-8F6C72D2CB26" refContainerID="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" propertyTargetId="1243C675-86A2-977F-2EFA-8F6C72D2CB26"/>
-   <object objectType="FKIndexAssociation" objectID="6A45C1C6-8C3B-317C-9221-BA841A05B730" name="Metadata_Music_FK" containerID="D1128F38-5763-FC3D-4FB1-14F78EDBE4CB" refContainerID="25DE0936-5106-79A2-1678-9EAA1E0DA843" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="25DE0936-5106-79A2-1678-9EAA1E0DA843" propertyTargetId="D1128F38-5763-FC3D-4FB1-14F78EDBE4CB"/>
-   <object objectType="FKIndexAssociation" objectID="6AA622A5-D308-C63C-2AF6-730CF06EBF34" name="History_User_FK" containerID="F0AD5A40-5659-C806-BEA1-595FD0DB5F39" refContainerID="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" propertyTargetId="F0AD5A40-5659-C806-BEA1-595FD0DB5F39"/>
-   <object objectType="FKIndexAssociation" objectID="B59DC6EC-C75B-86D4-AFA3-705630B49873" name="Playlist_has_Music_Music_FK" containerID="47A181FD-9D20-6987-2EAE-0B7F53C88FB3" refContainerID="25DE0936-5106-79A2-1678-9EAA1E0DA843" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="25DE0936-5106-79A2-1678-9EAA1E0DA843" propertyTargetId="47A181FD-9D20-6987-2EAE-0B7F53C88FB3"/>
-   <object objectType="FKIndexAssociation" objectID="C7DC4550-6D2C-B38B-5C23-5E37D6D8832D" name="Preferences_User_FK" containerID="D088A558-CA22-9A96-F938-4F7712E4AEF1" refContainerID="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" propertyTargetId="D088A558-CA22-9A96-F938-4F7712E4AEF1"/>
+   <object objectType="Table" objectID="1243C675-86A2-977F-2EFA-8F6C72D2CB26" name="Statistics" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.Table" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="" propertyTargetId=""/>
+   <object objectType="Table" objectID="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" name="User" seqName="seg_0" propertyClassName="oracle.dbtools.crest.model.design.relational.Table" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="" propertyTargetId=""/>
+   <object objectType="FKIndexAssociation" objectID="14761BF2-0284-F09E-1C36-5AD59C18B84E" name="History_Music_FK" seqName="seg_0" containerID="F0AD5A40-5659-C806-BEA1-595FD0DB5F39" refContainerID="25DE0936-5106-79A2-1678-9EAA1E0DA843" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="25DE0936-5106-79A2-1678-9EAA1E0DA843" propertyTargetId="F0AD5A40-5659-C806-BEA1-595FD0DB5F39"/>
+   <object objectType="FKIndexAssociation" objectID="6AA622A5-D308-C63C-2AF6-730CF06EBF34" name="History_User_FK" seqName="seg_0" containerID="F0AD5A40-5659-C806-BEA1-595FD0DB5F39" refContainerID="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" propertyTargetId="F0AD5A40-5659-C806-BEA1-595FD0DB5F39"/>
+   <object objectType="FKIndexAssociation" objectID="6A45C1C6-8C3B-317C-9221-BA841A05B730" name="Metadata_Music_FK" seqName="seg_0" containerID="D1128F38-5763-FC3D-4FB1-14F78EDBE4CB" refContainerID="25DE0936-5106-79A2-1678-9EAA1E0DA843" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="25DE0936-5106-79A2-1678-9EAA1E0DA843" propertyTargetId="D1128F38-5763-FC3D-4FB1-14F78EDBE4CB"/>
+   <object objectType="FKIndexAssociation" objectID="B59DC6EC-C75B-86D4-AFA3-705630B49873" name="Playlist_has_Music_Music_FK" seqName="seg_0" containerID="47A181FD-9D20-6987-2EAE-0B7F53C88FB3" refContainerID="25DE0936-5106-79A2-1678-9EAA1E0DA843" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="25DE0936-5106-79A2-1678-9EAA1E0DA843" propertyTargetId="47A181FD-9D20-6987-2EAE-0B7F53C88FB3"/>
+   <object objectType="FKIndexAssociation" objectID="518E00B2-30C8-083A-0841-D61034BE188E" name="Playlist_has_Music_Playlist_FK" seqName="seg_0" containerID="47A181FD-9D20-6987-2EAE-0B7F53C88FB3" refContainerID="0AF231FE-3CA2-BFD0-E42B-0DFDC72D4D26" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="0AF231FE-3CA2-BFD0-E42B-0DFDC72D4D26" propertyTargetId="47A181FD-9D20-6987-2EAE-0B7F53C88FB3"/>
+   <object objectType="FKIndexAssociation" objectID="C7DC4550-6D2C-B38B-5C23-5E37D6D8832D" name="Preferences_User_FK" seqName="seg_0" containerID="D088A558-CA22-9A96-F938-4F7712E4AEF1" refContainerID="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" propertyTargetId="D088A558-CA22-9A96-F938-4F7712E4AEF1"/>
+   <object objectType="FKIndexAssociation" objectID="51EE3780-3B5D-E1A1-65B0-7ED699DD5948" name="Statistics_User_FK" seqName="seg_0" containerID="1243C675-86A2-977F-2EFA-8F6C72D2CB26" refContainerID="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" propertyClassName="oracle.dbtools.crest.model.design.relational.FKIndexAssociation" propertyParentId="C5DFC5DD-35E9-B422-B2BF-B7648E7DE99B" propertySourceId="175D64CD-6D93-E0AE-DD13-FF75CAB2DC92" propertyTargetId="1243C675-86A2-977F-2EFA-8F6C72D2CB26"/>
 </oracle.dbtools.crest.model.design.relational.RelationalDesign>
diff --git a/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/subviews/DDF9FCBE-2830-5AB6-3DD0-B2CFAA840673.xml b/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/subviews/DDF9FCBE-2830-5AB6-3DD0-B2CFAA840673.xml
index 3523de1..4dc1720 100644
--- a/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/subviews/DDF9FCBE-2830-5AB6-3DD0-B2CFAA840673.xml
+++ b/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/subviews/DDF9FCBE-2830-5AB6-3DD0-B2CFAA840673.xml
@@ -16,7 +16,7 @@
 <objectViews>
 <OView class="oracle.dbtools.crest.swingui.relational.TVTable" oid="0AF231FE-3CA2-BFD0-E42B-0DFDC72D4D26" otype="Table" vid="EE21C7FE-C85E-5A2F-1C78-65A01371BC3B">
 <hideElementsInCurrentOnly>false</hideElementsInCurrentOnly>
-<bounds x="4" y="390" width="253" height="110"/>
+<bounds x="4" y="390" width="253" height="140"/>
 </OView>
 <OView class="oracle.dbtools.crest.swingui.relational.TVTable" oid="1243C675-86A2-977F-2EFA-8F6C72D2CB26" otype="Table" vid="96F7DC31-5392-F6F5-90A9-53BD7AAFBAD7">
 <hideElementsInCurrentOnly>false</hideElementsInCurrentOnly>
diff --git a/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/table/seg_0/0AF231FE-3CA2-BFD0-E42B-0DFDC72D4D26.xml b/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/table/seg_0/0AF231FE-3CA2-BFD0-E42B-0DFDC72D4D26.xml
index 0451d83..6fbfb7e 100644
--- a/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/table/seg_0/0AF231FE-3CA2-BFD0-E42B-0DFDC72D4D26.xml
+++ b/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/table/seg_0/0AF231FE-3CA2-BFD0-E42B-0DFDC72D4D26.xml
@@ -8,6 +8,17 @@
 <existDependencyGenerateInDDl>true</existDependencyGenerateInDDl>
 <parsed>true</parsed>
 <columns itemClass="oracle.dbtools.crest.model.design.relational.Column">
+<Column name="playlist_unique_id" id="A47AFEAF-BC88-3249-5ABE-C76700BAC437">
+<createdBy>Javier Alonso Silva</createdBy>
+<createdTime>2018-06-23 10:17:02 UTC</createdTime>
+<ownerDesignName>database_design</ownerDesignName>
+<useDomainConstraints>false</useDomainConstraints>
+<use>1</use>
+<logicalDatatype>LOGDT024</logicalDatatype>
+<dataTypeSize>256 CHAR</dataTypeSize>
+<ownDataTypeParameters>256 CHAR,,</ownDataTypeParameters>
+<autoIncrementCycle>false</autoIncrementCycle>
+</Column>
 <Column name="playlist_id" id="9961C1BD-DFE5-9B3E-1C5F-5FEAC633680C">
 <createdBy>Javier Alonso Silva</createdBy>
 <createdTime>2018-06-18 14:51:13 UTC</createdTime>
@@ -44,6 +55,28 @@
 <ownDataTypeParameters>,,</ownDataTypeParameters>
 <autoIncrementCycle>false</autoIncrementCycle>
 </Column>
+<Column name="playlist_quality" id="E2D34E29-DF92-4B69-860D-15FFCBDDA43F">
+<createdBy>Javier Alonso Silva</createdBy>
+<createdTime>2018-06-23 10:17:02 UTC</createdTime>
+<ownerDesignName>database_design</ownerDesignName>
+<nullsAllowed>true</nullsAllowed>
+<useDomainConstraints>false</useDomainConstraints>
+<use>1</use>
+<logicalDatatype>LOGDT011</logicalDatatype>
+<ownDataTypeParameters>,,</ownDataTypeParameters>
+<autoIncrementCycle>false</autoIncrementCycle>
+</Column>
+<Column name="playlist_format" id="F6634F13-C5A1-CF16-A041-FF4A600E4D7D">
+<createdBy>Javier Alonso Silva</createdBy>
+<createdTime>2018-06-23 10:17:02 UTC</createdTime>
+<ownerDesignName>database_design</ownerDesignName>
+<nullsAllowed>true</nullsAllowed>
+<useDomainConstraints>false</useDomainConstraints>
+<use>1</use>
+<logicalDatatype>LOGDT011</logicalDatatype>
+<ownDataTypeParameters>,,</ownDataTypeParameters>
+<autoIncrementCycle>false</autoIncrementCycle>
+</Column>
 </columns>
 <indexes itemClass="oracle.dbtools.crest.model.design.relational.Index">
 <ind_PK_UK id="0AAA742E-85E9-ABBB-3457-D0D166522D31" name="Playlist_PK">
@@ -55,7 +88,7 @@
 <indexState>Primary Constraint</indexState>
 <isSurrogateKey>false</isSurrogateKey>
 <indexColumnUsage>
-<colUsage columnID="9961C1BD-DFE5-9B3E-1C5F-5FEAC633680C"/>
+<colUsage columnID="A47AFEAF-BC88-3249-5ABE-C76700BAC437"/>
 </indexColumnUsage>
 </ind_PK_UK>
 </indexes>
diff --git a/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/table/seg_0/175D64CD-6D93-E0AE-DD13-FF75CAB2DC92.xml b/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/table/seg_0/175D64CD-6D93-E0AE-DD13-FF75CAB2DC92.xml
index 40a1315..b0a110b 100644
--- a/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/table/seg_0/175D64CD-6D93-E0AE-DD13-FF75CAB2DC92.xml
+++ b/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/table/seg_0/175D64CD-6D93-E0AE-DD13-FF75CAB2DC92.xml
@@ -44,6 +44,17 @@
 <ownDataTypeParameters>,,</ownDataTypeParameters>
 <autoIncrementCycle>false</autoIncrementCycle>
 </Column>
+<Column name="first_use" id="36E601DB-7FA4-6D6B-C3DD-74BA6E8C9000">
+<createdBy>Javier Alonso Silva</createdBy>
+<createdTime>2018-06-23 11:12:16 UTC</createdTime>
+<ownerDesignName>database_design</ownerDesignName>
+<nullsAllowed>true</nullsAllowed>
+<useDomainConstraints>false</useDomainConstraints>
+<use>1</use>
+<logicalDatatype>LOGDT008</logicalDatatype>
+<ownDataTypeParameters>,,</ownDataTypeParameters>
+<autoIncrementCycle>false</autoIncrementCycle>
+</Column>
 </columns>
 <indexes itemClass="oracle.dbtools.crest.model.design.relational.Index">
 <ind_PK_UK id="D02538CD-C7A9-1C9E-7706-9BD9CDCB8B5D" name="User_PK">
diff --git a/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/table/seg_0/47A181FD-9D20-6987-2EAE-0B7F53C88FB3.xml b/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/table/seg_0/47A181FD-9D20-6987-2EAE-0B7F53C88FB3.xml
index 3eb66f1..72c5915 100644
--- a/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/table/seg_0/47A181FD-9D20-6987-2EAE-0B7F53C88FB3.xml
+++ b/Design/DB_STRUCTURE/database_design/rel/C5DFC5DD-B7648E7DE99B/table/seg_0/47A181FD-9D20-6987-2EAE-0B7F53C88FB3.xml
@@ -7,9 +7,9 @@
 <existDependencyGenerateInDDl>true</existDependencyGenerateInDDl>
 <parsed>true</parsed>
 <columns itemClass="oracle.dbtools.crest.model.design.relational.Column">
-<Column name="Playlist_playlist_id" id="F4245181-B774-E93A-39C8-0A248335545E">
+<Column name="playlist_unique_id" id="12CD1F60-BC0A-AD30-C213-ECD568579AA8">
 <createdBy>Javier Alonso Silva</createdBy>
-<createdTime>2018-06-18 14:51:13 UTC</createdTime>
+<createdTime>2018-06-23 10:17:02 UTC</createdTime>
 <ownerDesignName>database_design</ownerDesignName>
 <useDomainConstraints>false</useDomainConstraints>
 <use>1</use>
@@ -19,7 +19,7 @@
 <previousColumn>false</previousColumn>
 <autoIncrementCycle>false</autoIncrementCycle>
 <associations>
-<colAssociation fkAssociation="518E00B2-30C8-083A-0841-D61034BE188E" referredColumn="9961C1BD-DFE5-9B3E-1C5F-5FEAC633680C"/>
+<colAssociation fkAssociation="518E00B2-30C8-083A-0841-D61034BE188E" referredColumn="A47AFEAF-BC88-3249-5ABE-C76700BAC437"/>
 </associations>
 </Column>
 <Column name="Music_file_id" id="3132AE0E-35F7-D5FB-7991-D900AE22AD43">
@@ -37,28 +37,6 @@
 <colAssociation fkAssociation="B59DC6EC-C75B-86D4-AFA3-705630B49873" referredColumn="1F1E7DDA-F1AD-9264-27B3-CC9CC8B4A8FB"/>
 </associations>
 </Column>
-<Column name="playlist_quality" id="37D138F2-15D2-216D-04B4-9E7D510E4AB4">
-<createdBy>Javier Alonso Silva</createdBy>
-<createdTime>2018-06-20 19:09:34 UTC</createdTime>
-<ownerDesignName>database_design</ownerDesignName>
-<nullsAllowed>true</nullsAllowed>
-<useDomainConstraints>false</useDomainConstraints>
-<use>1</use>
-<logicalDatatype>LOGDT011</logicalDatatype>
-<ownDataTypeParameters>,,</ownDataTypeParameters>
-<autoIncrementCycle>false</autoIncrementCycle>
-</Column>
-<Column name="playlist_format" id="8C829605-2812-5AB3-DA74-D18B5CDF8A18">
-<createdBy>Javier Alonso Silva</createdBy>
-<createdTime>2018-06-20 19:09:45 UTC</createdTime>
-<ownerDesignName>database_design</ownerDesignName>
-<nullsAllowed>true</nullsAllowed>
-<useDomainConstraints>false</useDomainConstraints>
-<use>1</use>
-<logicalDatatype>LOGDT011</logicalDatatype>
-<ownDataTypeParameters>,,</ownDataTypeParameters>
-<autoIncrementCycle>false</autoIncrementCycle>
-</Column>
 </columns>
 <indexes itemClass="oracle.dbtools.crest.model.design.relational.Index">
 <ind_PK_UK id="26077F0B-DF80-4C22-9679-E91111201BFD" name="Playlist_has_Music_PK">
@@ -69,8 +47,8 @@
 <indexState>Primary Constraint</indexState>
 <isSurrogateKey>false</isSurrogateKey>
 <indexColumnUsage>
-<colUsage columnID="F4245181-B774-E93A-39C8-0A248335545E"/>
 <colUsage columnID="3132AE0E-35F7-D5FB-7991-D900AE22AD43"/>
+<colUsage columnID="12CD1F60-BC0A-AD30-C213-ECD568579AA8"/>
 </indexColumnUsage>
 </ind_PK_UK>
 <ind_PK_UK id="2E42E7DB-DC1C-B6A6-1678-89DFBEE716F9" name="Playlist_has_Music_Playlist_FK">
@@ -81,7 +59,7 @@
 <indexState>Foreign Key</indexState>
 <isSurrogateKey>false</isSurrogateKey>
 <indexColumnUsage>
-<colUsage columnID="F4245181-B774-E93A-39C8-0A248335545E"/>
+<colUsage columnID="12CD1F60-BC0A-AD30-C213-ECD568579AA8"/>
 </indexColumnUsage>
 </ind_PK_UK>
 <ind_PK_UK id="40965CD0-1F34-A725-D6F7-9DE5157A00AD" name="Playlist_has_Music_Music_FK">