CONCAT not working

[David Villalobos Cambronero]

Hi,

I have the following procedure, there is a variable called sDestinatarios, inside of it I concatenate some some other values, but in the time of showing it is empty (NULL).

My question is: what I'm doing wrong?

Best regards
David

delimiter |

DROP PROCEDURE IF EXISTS `PruebaMercadeo` |
CREATE PROCEDURE `PruebaMercadeo`()
LANGUAGE SQL
DETERMINISTIC
SQL SECURITY DEFINER
MODIFIES SQL DATA
COMMENT 'Guarda o modifica datos en la tabla Mercadeo_Envios'
BEGIN

DECLARE `iFinalCursor` TINYINT DEFAULT 0;
DECLARE `sDestinatario` VARCHAR(310);
DECLARE `iClasificacion` SMALLINT UNSIGNED DEFAULT 0;
DECLARE `sDestinatarios` MEDIUMTEXT;
DECLARE `bSalir` BOOL DEFAULT FALSE;
DECLARE `iPosicionInicio` INT DEFAULT 1;
DECLARE `iPosicionFinal` INT DEFAULT 0;

DECLARE `cDestinatarios` CURSOR FOR SELECT User FROM `mysql`.`user`;
DECLARE `cUsers` CURSOR FOR SELECT * FROM `tmpDestinatarios`;

DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET `iFinalCursor` = 1;

DROP TABLE IF EXISTS `tmpDestinatarios`;
CREATE TEMPORARY TABLE `tmpDestinatarios` (`Destinatario` VARCHAR(310) COLLATE utf8_spanish_ci) ENGINE = MEMORY DEFAULT CHARSET = utf8;


OPEN `cDestinatarios`;
CICLOCorreos: LOOP
FETCH `cDestinatarios` INTO `sDestinatario`;
IF `iFinalCursor` = 1 THEN LEAVE CICLOCorreos; END IF;
INSERT INTO `tmpDestinatarios` VALUES (`sDestinatario`);
END LOOP CICLOCorreos;
CLOSE `cDestinatarios`;

SELECT * FROM `tmpDestinatarios`;

SET `iFinalCursor` = 0;
OPEN `cUsers`;
CICLOCorreos: LOOP
FETCH `cUsers` INTO `sDestinatario`;
IF `iFinalCursor` = 1 THEN LEAVE CICLOCorreos; END IF;
SET `sDestinatarios` = CONCAT(`sDestinatarios`, `sDestinatario`);
END LOOP CICLOCorreos;
CLOSE `cUsers`;

SELECT `sDestinatarios`; #Why this is NULL?

END |


DELIMITER ;