Hi,
My application uses the below query
SELECT TXN_DT, INTEGER (CLNT_SRF_NO) AS CLNT_SRF_NO,(TXN_AMT * EXCH_RT) AS TXN_AMT FROM PQ5.SRVC_PLATF_CLNT_TXN_DTL
UNION ALL
SELECT TXN_DT, INTEGER (CLNT_SRF_NO) AS CLNT_SRF_NO,(TXN_AMT * EXCH_RT) AS TXN_AMT FROM PQ5.ABM_DEP_TXN_DTL
UNION ALL
SELECT TXN_DT, INTEGER (CLNT_SRF_NO) AS CLNT_SRF_NO , (TXN_AMT * EXCH_RT) AS TXN_AMT FROM PQ5.HSCP_DEP_TXN_DTL

It takes very much time, please provide soem input to fine tune the query.

Thanks
Surjya

Since there is no WHERE clause in the queries, it is having to read and return every row in each table. How many rows are there in each table?

As Marcus mentioned, no where clause not much to improve. The only thing that may help is to create an index on the four columns you are after. Depending on the version you are running you may want to create and index on expressions, meaning the column definition would be:
Dave