Creating temporary tables in MySQL Stored Procedure

Question

The following procedure gives me an error when I invoke it using the CALL statement:

CREATE DEFINER=`user`@`localhost` PROCEDURE `emp_performance`(id VARCHAR(10))
BEGIN
DROP TEMPORARY TABLE IF EXISTS performance;
CREATE TEMPORARY TABLE performance AS  
    SELECT time_in, time_out, day FROM attendance WHERE employee_id = id;
END

The error says "Unknown table 'performance' " .

This is my first time actually using stored procedures and I got my sources from Google. I just cant figure out what I am doing wrong.

Answer 1

I've tidied it up a little for you and added example code. I always keep my parameter names the same as the fields they represent but prefix with p_ which prevents issues. I do the same with variables declared in the sproc body but prefix with v_.

You can find another one of my examples here:

Generating Depth based tree from Hierarchical Data in MySQL (no CTEs)

drop procedure if exists emp_performance;

delimiter #

create procedure emp_performance
(
in p_employee_id varchar(10)
)
begin

declare v_counter int unsigned default 0;

create temporary table tmp engine=memory select time_in, time_out 
 from attendance where employee_id = p_employee_id;

-- do stuff with tmp...

select count(*) into v_counter from tmp;

-- output and cleanup

select * from tmp order by time_in;

drop temporary table if exists tmp;

end#

delimiter ;

call emp_performance('E123456789');

Answer 2

By default MySQL config variable sql_notes is set to 1.

That means that DROP TEMPORARY TABLE IF EXISTS performance; increments warning_count by one and you get a warning when a stored procedure finishes.

You can set sql_notes variable to 0 in my.cnf or rewrite stored procedure like that:

CREATE DEFINER=`user`@`localhost` PROCEDURE `emp_performance`(id VARCHAR(10))
BEGIN
SET @@session.sql_notes = 0;
DROP TEMPORARY TABLE IF EXISTS performance;
CREATE TEMPORARY TABLE performance AS  
    SELECT time_in, time_out, day FROM attendance WHERE employee_id = id;
SET @@session.sql_notes = 1;
END