Stored procedure error on CALL - mysql

Question

I am trying to call a procedure which compiles successfully but on calling I get this error:
Query: call proc5
Error Code: 1064
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'NULL' at line 1
This is my Stored procedure:
DELIMITER $$
CREATE DEFINER = `root` #`localhost` PROCEDURE `proc5` ()
BEGIN
DECLARE done BOOL DEFAULT FALSE ;
DECLARE tablename VARCHAR (100) ;
DECLARE tracktables CURSOR FOR
SELECT
TABLE_NAME
FROM
information_schema.TABLES
WHERE TABLE_SCHEMA = 'db1' ;
DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = TRUE ;
OPEN tracktables ;
myloop :
LOOP
FETCH tracktables INTO tablename ;
IF done
THEN CLOSE tracktables ;
LEAVE myloop ;
END IF ;
SET #s = CONCAT(
'INSERT INTO db2.test1 SELECT * FROM ',
#tablename
) ;
PREPARE stmt1 FROM #s ;
EXECUTE stmt1 ;
DEALLOCATE PREPARE stmt1 ;
END LOOP ;
END $$
DELIMITER ;
Actually, I want to select all the tables from a database and insert those tables into one table which is in another database using MySQL Cursors. And when I call this stored procedure I get the above error.

Answer 1

The problem is that you are mixing declared variables and impromtu #vars.
var -> tablename does not equal var -> #tablename.
Change the set line to:
SET #s = CONCAT(
'INSERT INTO db2.test1 SELECT * FROM `'
,tablename
,'`'
) ;
Now it should work.
The backticks ` should not be needed, but are there just in case.