Q: I am having difficulty in setting up an update query. The scenario follows:
File A: Cust# Taxfield File B: CustNo Taxkey
The basic dilemma is how to update the Taxfield in file A, when the Taxkey in file B equals a certain value. For example:
If A:Cust# = B:Custno and B:Taxkey = NY540 Change A:Taxfield to NY50
Here's the SQL statement I have developed thus far:
Update A set Taxfield = 'NY50' where Cust# = all (select Custno from B where Taxkey = 'NY540')
This statement ends up selecting the proper records from file B, but not updating file A. Where's my mistake?
A: You should be using the IN predicate instead of the quantified predicate '= all'. The result of the '= all' predicate is true only if the subselect returns no values or the relationship is true for every value returned by the subselect.
In your case, the subselect is returning more than one Custno in file B where Taxkey = 'NY540'. Cust# from file A is not equal to every customer returned; therefore, the predicate is not true.