Comments on: Reference a query object from another query http://itknowledgeexchange.techtarget.com/itanswers/reference-a-query-object-from-another-query/ Sat, 25 May 2013 00:24:16 +0000 hourly 1 By: steveg44 http://itknowledgeexchange.techtarget.com/itanswers/reference-a-query-object-from-another-query/#comment-39146 steveg44 Thu, 03 Nov 2005 13:17:28 +0000 #comment-39146 mdaponte reported the SQL Server 2000 inner query technique. This also works with DB2 UDB.

Further, UDB provides the following construct, a common-table-expression, that makes for an even simpler to understand query…

WITH query_data (field1, field2) AS
(SELECT xxx, yyy FROM some_table WHERE …)
SELECT t1.field1,
q1.field2
FROM table_data t1, query_data q1
WHERE t1.field1 = q1.field1

This example also uses correlated coefficients for ease of coding JOIN conditions. Note that it isn’t necessary to retrieve q1.field1 since it will always have the same value as t1.field1.

Note that the complete query_data result set is not available outside the full select statement so this technique is valid only if you only want the end result.

]]> By: mdaponte http://itknowledgeexchange.techtarget.com/itanswers/reference-a-query-object-from-another-query/#comment-39147 mdaponte Thu, 27 Oct 2005 10:09:28 +0000 #comment-39147 You could create a view with the query, and then you could use it in any query:

create view xxx as
select …

And I guess that you could also use it as a inner query (at least in SQL Server 2000 you could), for example:

select *
from table1, (select t2.x, y, z
from table2 t2, table3 t3
where t2.x = t3.x) as new_table
where table1.x = new_table.x

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