I have 2 queries: the first query result will be passed to the second query using a user-defined variable. (This implementation is because of a performance issue with the table after applying proper indexing on large scale database)
The queries look like this:
SET @some_var=''; SELECT sids INTO @some_var FROM fsettings WHERE cid=1 AND tid=9 AND tp=1 AND IsDelete=0; SELECT name FROM `tlivewsts` WHERE id IN( @some_var ) ORDER BY FIELD( id, @some_var );
I get a result within 1-2 sec. (before it was 30 sec.)
However, my issue is what happens if the first query returns no result (empty variable). Then, the second query throws awarning in mysql.
My question is: Is there any possible way to check whether the user-defined variable contains no result, and then directly return "0 results found"? I know this can be done through function/sp in MariaDB; I want to know if that is possible using a simple query?
I have gone through MySQL user-defined variable in WHERE clause for reference, without finding a solution.