Better Option Than UNION

Hi there,

I am selecting few records from a particular table and however I need to run the same query using UNION.But its taking long to execute the query.If I run the query as 2 parts then it works fine but if I put in UNION to both queries then I have problem.Can anyone help?

eg:

Select '' as name,'' as userid,'' as firstname from table1 where user like 'A%'(works fine)

Select name,userid,firstname from table1 where user like 'A%'(also works fine)


but if I user

Select '' as name,'' as userid,'' as firstname from table1 where user like 'A%'
UNION
Select name,userid,firstname from table1 where user like 'A%'

its taking too long

Somebody please help me