Posted by Erland Sommarskog on 05/02/07 07:10

meendar (askjavaprogrammers@gmail.com) writes:
> I have selected a field name and declared it as varchar, since it is
> varchar in table and performed some numeric operation with numbers,
>
> even after i cast the sql in below code, it throws an exception as
> "Error converting data type varchar to numeric."
>
>...
> Declare r1 cursor
> local Scroll Keyset Optimistic
> For
> select z1 from employee a1 where z2= @z1 + 45 .....
>
>
> I want to clear that how can we cast the field with varchar for
> numeric operations, i have also tried cast and convert to change it
> but all in vain.

SQL Server tries to convert all values in employee.z2 to numeric, and
when this fails for some value, the query fails.

You need to use the CASE expression:

WHERE CASE WHEN ltrim(rtrim(z2)) NOT LIKE '%[^0-9]%'
THEN convert(numeric, z2)
END = @z1 + 45

Now it will only attempt to convert z2 which it consists of digits only.

--
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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