Update with Sub Query Derived Table Error

Question

I have the following SQL statement to simply update the #temp temp table with the latest package version number in our Sybase 15 database.

UPDATE t
SET versionId = l.latestVersion
FROM #temp t INNER JOIN (SELECT gp.packageId
                                , MAX(gp.versionId) latestVersion
                         FROM Group_Packages gp 
                         WHERE gp.groupId IN (SELECT groupId 
                                              FROM User_Group 
                                              WHERE userXpId = 'someUser')
                         GROUP BY gp.packageId) l
ON t.packageId = l.packageId

To me (mainly Oracle & SQL Server experience more than Sybase) there is little wrong with this statement. However, Sybase throws an exception:

You cannot use a derived table in the FROM clause of an UPDATE or DELETE statement.

Now, I don't get what the problem is here. I assume it is because of the aggregation / GROUP BY being used. Of course, I could put the sub query in a temp table and join on it but I really want to know what the 'correct' method should be and what the hell is wrong.

Any ideas or guidance would be much appreciated.

Answer 1

I guess this is a limitation of Sybase (not allowing derived tables) in the FROM clause of the UPDATE. Perhaps you can rewrite like this:

UPDATE t
SET t.versionId = l.versionId
FROM #temp t
  INNER JOIN 
    Group_Packages l
      ON t.packageId = l.packageId
WHERE
    l.groupId IN ( SELECT groupId 
                   FROM User_Group 
                   WHERE userXpId = 'someUser')
  AND
    l.versionId =
        ( SELECT MAX(gp.versionId)
          FROM Group_Packages gp 
          WHERE gp.groupId IN ( SELECT groupId 
                                FROM User_Group 
                                WHERE userXpId = 'someUser')
            AND gp.packageId = l.packageId
        ) ;

Answer 2

It seems that SYBASE doesn't support nested queries in UPDATE FROM class. Similar problem

Try to use this:

UPDATE #temp
SET versionId =  (SELECT MAX(gp.versionId) latestVersion
                         FROM Group_Packages gp 
                         WHERE gp.packageId=#temp.packageId
                                and
                               gp.groupId IN (SELECT groupId 
                                              FROM User_Group 
                                              WHERE userXpId = 'someUser')

                         )

And also what if l.latestVersion is NULL? Do you want update #temp with null ? if not then add WHERE:

    WHERE (SELECT MAX(gp.versionId)
                          ....
                                 ) is not null

Answer 3

Your table alias for #temp is called "t" and your original table is called "t".

My guess is that this is the problem.

I think you want to start with:

update #temp