How to understand a mysql temporary table already exists in a stored procedure?

Question

I use mysql temporary table to share some middle data between several stored procedures. All of these procedures use a single database connection. In every SP, I need to determine a if mysql temporary table already exists or not. if it already exists, then I'll use it's values, otherwise the SP will create & fill temporary table & other SPs (on same connection of course!) will use temporary table results.

But I don't know how should I check if the temporary table already exists or not, I mean something like this:

IF temporaryTablename EXISTS THEN
   ...
ELSE
   ...
END IF;

any idea?

Answer 1

It has the IF NOT EXISTS (13.1.17. CREATE TABLE Syntax) option when creating a table, you can use in this case.

Example:

DELIMITER $$

CREATE PROCEDURE `temp_sp1`()
BEGIN
    CREATE TEMPORARY TABLE IF NOT EXISTS `temp_table` (
      `col2` int(11) DEFAULT NULL,
      `col3` int(11) DEFAULT NULL
    );
    INSERT INTO `temp_table` (`col2`, `col3`) VALUES (4, 5);
    SELECT `col2`, `col3` FROM `temp_table`;
END$$

DELIMITER ;

SQL Fiddle demo

UPDATE

...
DECLARE `no_such_table` TINYINT(1) DEFAULT 0;
DECLARE CONTINUE HANDLER FOR SQLSTATE VALUE '42S02' SET `no_such_table` := 1;
DO (SELECT NULL FROM `temp_table` LIMIT 0);
IF (`no_such_table`) THEN
   ...  
ELSE
   ...  
END IF;
...