Small mysql loop for generating unique alphanumerical codes

random-code-generator.sql

DROP PROCEDURE IF EXISTS generator; 

DELIMITER //

CREATE PROCEDURE generator(total INTEGER UNSIGNED, max_chars INTEGER UNSIGNED)
BEGIN
    SET @currentLoop = 0;
    
    REPEAT
    
    	SET @code = '';
   
    	WHILE LENGTH(@code) < max_chars DO
        	SET @code = CONCAT(@code, substring('ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789', rand(round(rand()*4294967296))*36+1, 1));
    	END WHILE;
    
        # OUR TABLE expects to have a column 'code' with an unique constraint. With the IGNORE statement, any duplicate codes will not get inserted.    
    	INSERT IGNORE INTO randoms SET code = @code;

    	SET @currentLoop = @currentLoop + 1;
    
    UNTIL @currentLoop >= total END REPEAT;
END //
 
DELIMITER ;

# Here we trigger the generate procedure. Two arguments are expected: first the total amount of codes, secondly the length of each generated code.
# In the example below we generate 1000 codes with each a length of 8 characters.
CALL generator(1000, 8);