title: where to place CASE WHEN column IS NULL in this query
body: <p>I'm having some trouble translating an MS Access query to SQL:</p>
  
  <pre><code>SELECT id, col1, col2, col3
  FROM table1
  
  LEFT OUTER JOIN table2
  ON table1.id = table2.id
  
  LEFT OUTER JOIN table3
  ON table1.id = table3.id
  </code></pre>
  
  <p>so far so good, but here's the (CASE) part where I get stuck:</p>
  
  <pre><code>CASE WHEN table3.col3 IS NULL THEN table2.col3 AS col4 ELSE table3.col3 as col4
  </code></pre>
  
  <p>I know the above line doesn't work, but hopefully it hints at what I'm trying to accomplish. Thanks!</p>
  
  <p>UPDATE: All of the suggestions so far have resulted in "Incorrect syntax near the keyword 'AS'" error, so maybe there's something else I'm missing. Below the actual query. The issue is that we have two tables, both with and EUID column. If dbo.EU_Admin3.EUID is not NULL, it takes precedence in the join. If dbo.EU_Admin3.EUID is NULL, use dbo.EU_Admin2.EUID instead. Hope that clarifies this.</p>
  
  <pre><code>SELECT dbo.AdminID.CountryID, dbo.AdminID.CountryName, dbo.AdminID.RegionID, 
  dbo.AdminID.[Region name], dbo.AdminID.DistrictID, dbo.AdminID.DistrictName,
  dbo.AdminID.ADMIN3_ID, dbo.AdminID.ADMIN3 
  (CASE WHEN dbo.EU_Admin3.EUID IS NULL THEN dbo.EU_Admin2.EUID ELSE dbo.EU_Admin3.EUID END AS EUID)
  FROM dbo.AdminID 
  
  LEFT OUTER JOIN dbo.EU_Admin2
  ON dbo.AdminID.DistrictID = dbo.EU_Admin2.DistrictID
  
  LEFT OUTER JOIN dbo.EU_Admin3
  ON dbo.AdminID.ADMIN3_ID = dbo.EU_Admin3.ADMIN3_ID
  </code></pre>