title: SQL Server 2008 modify data type of table column
body: <p>I need to modify the data type of a table column which is considered to be done via the statement:</p>
  
  <pre><code>ALTER TABLE QUANTITIES_NEW ALTER COLUMN VERSION_NEW VARCHAR(12);
  </code></pre>
  
  <p>Unfortunately I go an error (German)</p>
  
  <pre><code>Meldung 5074, Ebene 16, Status 1, Zeile 1
  Das Objekt-Objekt 'UQ_QUANTITIES_NAME_VERSION' ist vom Spalte-Objekt 'VERSION_NEW' abhängig.
  Meldung 4922, Ebene 16, Status 9, Zeile 1
  Fehler bei ALTER TABLE ALTER COLUMN VERSION_NEW, da mindestens ein Objekt auf diese Spalte zugreift.
  </code></pre>
  
  <p>which can be translated to:</p>
  
  <pre><code>The object-object 'UQ_QUANTITIES_NAME_VERSION' depends on the column object 'VERSION_NEW'.
  Failure at ALTER TABLE ALTER COLUMN VERSION_NEW, because this column is accessed by one or more columns.
  </code></pre>
  
  <p>I assumed that the unique constraint isn't disabled. Therfore I executed the statement</p>
  
  <pre><code>ALTER TABLE QUANTITIES  NOCHECK CONSTRAINT ALL
  ;
  </code></pre>
  
  <p>too. But still the same error.</p>