user-creation-sql

DELIMITER $$
CREATE PROCEDURE create_user(username TEXT, passwordhash TEXT)
BEGIN
        DECLARE temp TEXT;
        SELECT user FROM mysql.user WHERE user = username INTO temp;
        IF temp = username THEN
                SIGNAL SQLSTATE '45002' SET MESSAGE_TEXT = 'username already exists';
        ELSE
                SET @s = CONCAT('CREATE USER \'', username, '\'@localhost IDENTIFIED BY PASSWORD \''+passwordhash+'\'');
                PREPARE stmt_create FROM @s;
                EXECUTE stmt_create;
                DEALLOCATE PREPARE stmt_create;
                FLUSH PRIVILEGES;
        END IF;
END $$