Perhaps this is obvious, but I have a SELECT (with many LEFT JOINs) that I would 
expect to return results, but it does not.  If I make one change in the order 
in which tables are used, the SELECT works:

The SQL that doesn't work is:
-----------------------------------
SELECT T1.patentNumber, T1.title, T2.ipvMap, T3.claimCode, T2.numOfFC, T2.numOfBC
FROM usptoDataTable AS T1
LEFT JOIN ipvDataTable AS T2 USING (patentNumber)
LEFT JOIN clientDataTable AS T3 USING (patentNumber)
LEFT JOIN iPlanetDataTable AS T4 USING (patentNumber)
WHERE T4.sunPatentNumber LIKE '%P%'
LIMIT 10
-----------------------------------

No rows are returned even though there are lots of rows in table T4 that fit the 
criteria.
Changing the order of the LEFT JOIN of T3 and T4 returns 10 rows. The SQL that works 
is:  
-----------------------------------
SELECT T1.patentNumber, T1.title, T2.ipvMap, T3.claimCode, T2.numOfFC, T2.numOfBC
FROM usptoDataTable AS T1
LEFT JOIN ipvDataTable AS T2 USING (patentNumber)
LEFT JOIN iPlanetDataTable AS T4 USING (patentNumber)    <---- order of these two is 
swapped but alias name unchanged
LEFT JOIN clientDataTable AS T3 USING (patentNumber)     <---- order of these two is 
swapped but alias name unchanged
WHERE T4.sunPatentNumber LIKE '%P%'
LIMIT 10
-----------------------------------

Is this a bug or user error?
Paul Albrecht



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