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Posted by Erland Sommarskog on 06/09/06 07:14
John (johnxhc@yahoo.com) writes:
> Unfortunately I did not write the parser, it is a generic component,
> passing me the following information
> 1) Field
> 2) Operation
> 3) Value
> I could replace all of the value above
> but the parser does not passing me the logic operator, even if it
> does, it is going to be very hard to for me to do a union because I
> could get very complicated logical operation and I could end up query
> the same table multiple time for different fields. Such as
> (Lastname='johnson' or firstname='smith') and (city='Los Angeles')
> or (productid in (234,23434,33) and (Lastname='Smith' or
> firstname='tom'))
Sounds like it's time to reconsider the solution from bottom up. Or accept
that you will never get a solution that performs well.
Not that I know that the UNION thing is going to run with lightning speed,
but the less degree of freedom you have, the poorer are you odds.
In any case, I feel that I cannot give much further advice, because there
is too much I don't know.
> also for "and" operation, I will need to do a intersection instead
> of union. I do not believe SQLServer provide this function on
> transaction sql.
INTERSECT is indeed a new operator, akin to UNION that was added in SQL
2005.
Although AND conditions are probably better implemented with regular AND
operators. They are far less devilish than the OR.
--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se
Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodinfo/previousversions/books.mspx
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