title: Create a calculated column from two different where statements in the same table using group by
body: <p>im trying to create a sql result which shows customers successrate(%) of their backupjobs. </p>
  
  <p>i somehow want to combine the following queries to achive this: </p>
  
  <pre><code>select [colCustomerID],count(*) as Totalbackups FROM [BackupStat].[dbo].[tblJobSummary] group by [colCustomerID]
  
  select [colCustomerID],count(*) as Failedbackups FROM [BackupStat].[dbo].[tblJobSummary] where [colStatus] !='Success' and [colStatus] !='Warning' group by [colCustomerID]
  </code></pre>
  
  <p>the result for the first query look something like this: </p>
  
  <pre><code>colCustomerID   Totalbackups
  EXK-1670001 315
  INK-2325001 8
  INK-995001  5
  INK-2326001 10
  INK-1729001 7
  INK-237001  2
  GBG-3795001 4
  INK-3422001 4
  INK-3768001 138
  INK-3780001 10
  </code></pre>