mysql drop table if exists inside procedure

Question

I'm trying to apply a nested set model example with procedures. I've found many of them with this technique and in the process I've found a problem. Every time I call the procedure I get unknown table XXX. When I create the procedure I got no problem at all. The quick example:

CREATE PROCEDURE `sp_getRoleTree` (IN root INT)
  READS SQL DATA
BEGIN
    DECLARE rows SMALLINT DEFAULT 0;
    DROP TABLE IF EXISTS ROLE_TREE;
    CREATE TABLE ROLE_TREE (
        nodeID INT PRIMARY KEY
    ) ENGINE=HEAP;

    INSERT INTO ROLE_TREE VALUES (root);

    SELECT * FROM ROLE_TREE;
    DROP TABLE ROLE_TREE;
END;

So my question is, am I doing something wrong here (it's example code), can I disable the warning on the if exists if the code is fine? Is there a special looping inside the procedures that's causing these kind of warnings?

Answer 1

As a work around: try to truncate table instead of re-creating.

Do not use DROP TABLE/CREATE TABLE. Create this table once (or when you need it) and use TRUNCATE TABLE command.