title: Query didn't update the rows which contains a specific values
body: <p>I want to update column called <code>target_ops_num</code> on case <code>if</code> column <code>technology</code> is <code>UMTS</code> then get value from <code>[MyNewDatabase].[dbo].[df_umts_carrier]</code> ELSE column <code>technology</code> is <code>GSM</code> then get the value from <code>[MyNewDatabase].[dbo].[df_gsm_carrier]</code> based on column <code>[MyNewDatabase].[dbo].[n_cell_name]</code></p>
  
  <p>as this is the query I created as the below one:</p>
  
  <pre><code>UPDATE [MyNewDatabase].[dbo].[df_umts_relation]
  SET [MyNewDatabase].[dbo].[df_umts_relation].[target_ops_num] = (CASE WHEN [MyNewDatabase].[dbo].[df_umts_relation].[technology] = 'UMTS' 
  THEN [MyNewDatabase].[dbo].[df_umts_carrier].[opsnum_umts] ELSE [MyNewDatabase].[dbo].[df_gsm_carrier].[opsnum_gsm] END)
  FROM [MyNewDatabase].[dbo].[df_umts_relation]
  LEFT JOIN [MyNewDatabase].[dbo].[df_umts_carrier]
  ON [n_cell_name] = [cell_name_umts]
  LEFT JOIN [MyNewDatabase].[dbo].[df_gsm_carrier]
  ON [n_cell_name] = [cell_name]
  </code></pre>
  
  <p>So the problem was the query takes about 18 min and didn't update the rows which contains column <code>technology</code> value <code>GSM</code> it updates the rows with column <code>technology</code> value <code>UMTS</code> only</p>
  
  <p>any one have a suugestion about this query?</p>