Hi,

Can someone help me understand this query:

SELECT attr1,attr2
FROM Table1
WHERE NOT EXISTS
(SELECT * FROM Table2
WHERE NOT EXISTS
(SELECT * FROM Table3
WHERE Table1.attr1=Table3.attr1 AND
Table2.attr10=Table3.attr10))

I don't really understand what the ( SELECT * FROM Table3 WHERE Table1.attr1=Table3.attr1 AND Table2.attr10=Table3.attr10) is doing. When I normally look at these queries, I would expect it to be ( Select * FROM Table3, table1, table2), but instead its just Table3.

Here is the data - http://www.picsend.net/images/385027table.bmp

If someone could help me out on this I would really appreciate it.

Thanks!