SQL Statement

Subject: SQL Statement
Newsgroups: comp.databases.oracle
Summary:
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Hi,

I have a sql statement which causes a very slow response. Can someone here help to check if the statement can be improved or better structured table.

I have 2 tables with the fillowing structures:

Table A				Table B
-------				-------
A1 PK				B1 PK
A2				B2 
A3				B3 

PK - Primary Key

The characteristic of Table B is that for B2 and B3 has a lot of repeated values.

Table B has a index on B1,B2,B3.

The problem SQL statement is as follows:

Select A1,A2,B1 from A,B
where A3 = B1 and

(B1 = variable_1 or

       B3 = variable_2);

However the performance is improved tremendously if the SQL statement is reconstructed in the following manner:

Select A1,A2,B1 from A,B
where A3 = B1 and

(B1 = variable_1);

Can someone suggest any possible way to improve the 1st mentioned SQL statement?

Thanks in Advance!!

Isaac
E-mail : wisaac_at_starnet.gov.sg Received on Wed Dec 06 1995 - 00:00:00 CET