Question

I have a complicated SELECT query that filters on a time range, and I want this time range (start and end dates) to be specifiable using user-supplied parameters. So I can use a stored procedure to do this, and the return is a multiple-row result set. The problem I’m having is how to deal with this result set afterwards. I can’t do something like:

SELECT * FROM (CALL stored_procedure(start_time, end_time))

even though the stored procedure is just a SELECT that takes parameters. Server-side prepared statement also don’t work (and they’re not persistent either).
Some suggest using temporary tables; the reason that’s not an ideal solution is that 1) I don’t want to specify the table schema and it seems that you have to, and 2) the lifetime of the temporary table would only be limited to a invocation of the query, it doesn’t need to persist beyond that.

So to recap, I want something like a persistent prepared statement server-side, whose return is a result set that MySQL can manipulate as if it was a subquery. Any ideas? Thanks.

By the way, I’m using MySQL 5.0. I know it’s a pretty old version, but this feature doesn’t seem to exist in any more recent version. I’m not sure whether SELECT-ing from a stored procedure is possible in other SQL engines; switching is not an option at the moment, but I’d like to know whether it’s possible anyway, in case we decide to switch in the future.

Answer 1

Selecting from functions is possible in other engines. For instance, Oracle allows you to write a function that returns a table of user defined type. You can define result sets in the function, fill them by using queries or even using a combination of selects and code. Eventually, the result set can be returned from the function, and you can continue to query on that by using:

select * from table(FunctionToBeCalls(parameters));

The only disadvantage, is that this result set is not indexed, so it might be slow if the function is used within a complex query.

In MySQL nothing like this is possible. There is no way to use a result set from a procedure directly in a select query. You can return single values from a function and you can use OUT or INOUT parameters to you procedure to return values from.
But entire result sets is not possible. Filling a temporary table within you procedure is the closest you will get.