title: Error when changing datatype of column in SQL Server DB - Java
body: <p>I made a query in Java which changes one column's datatype in another. It works fine until it tries to change type. It finds all columns in DB with specified datatype, but cannt change it.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>        st = conn.createStatement();
          rs = st.executeQuery("SELECT a.name as ColName, o.name AS TableName"
                  + "FROM sys.syscolumns AS a"
                  + "INNER JOIN sys.systypes AS b ON a.xtype = b.xtype AND b.name = 'char' AND a.length = 255"
                  + "INNER JOIN sys.objects AS o ON a.id = o.object_id WHERE (o.type = 'u') AND (o.schema_id = 1)");
          ResultSet rsPom;
          while (rs.next()){
              String tName=rs.getString("TableName");
              String cName=rs.getString("ColName");
              System.out.println(tName+"  "+cName);
              rsPom=st.executeQuery("ALTER TABLE "+ tName+" ALTER COLUMN "+cName+" nvarchar(255)");
          }
  </code></pre>
  
  <p>And here is my Exception:</p>
  
  <pre><code>com.microsoft.sqlserver.jdbc.SQLServerException: The object 'CK_TimeInstant_frame_default' is dependent on column 'frame'.
  at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(SQLServerException.java:216)
  at com.microsoft.sqlserver.jdbc.SQLServerStatement.getNextResult(SQLServerStatement.java:1515)
  at com.microsoft.sqlserver.jdbc.SQLServerStatement.doExecuteStatement(SQLServerStatement.java:792)
  at com.microsoft.sqlserver.jdbc.SQLServerStatement$StmtExecCmd.doExecute(SQLServerStatement.java:689)
  at com.microsoft.sqlserver.jdbc.TDSCommand.execute(IOBuffer.java:5696)
  at com.microsoft.sqlserver.jdbc.SQLServerConnection.executeCommand(SQLServerConnection.java:1715)
  at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeCommand(SQLServerStatement.java:180)
  at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeStatement(SQLServerStatement.java:155)
  at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeQuery(SQLServerStatement.java:616)
  at DataTypeChanger.changeDataType(DataTypeChanger.java:50)
  at DataTypeChanger.main(DataTypeChanger.java:36)
  </code></pre>
  
  <p>Does anyone knows what is all about, and what can I do?</p>