Multiple cursors in nested loops in MySQL

Question

I wish to do something which appear a bit complicated in MySQL. In fact, I wish to open a cursor, do a loop, and in this loop, open a second cursor using the data from the previ

Answer 1

DECLARE _idp INT;
DECLARE _cant INT;
DECLARE _rec INT;
DECLARE done INT DEFAULT 0;
-- Definición de la consulta
DECLARE primera CURSOR FOR SELECT dp.id_prod, SUM(dp.cantidad) AS cantidad, pp.receta FROM tm_detalle_pedido AS dp INNER JOIN tm_producto_pres AS pp
DECLARE segunda CURSOR FOR SELECT id_ins, cant FROM tm_producto_ingr WHERE id_pres = _idp;

-- Declaración de un manejador de error tipo NOT FOUND
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

-- Abrimos el primer cursor
OPEN primera;

REPEAT

FETCH primera INTO _idp, _cant, _rec;

IF NOT done THEN

 OPEN segunda;
 block2: BEGIN
     DECLARE doneLangLat INT DEFAULT 0;
     DECLARE _ii INT;
     DECLARE i FLOAT;
     DECLARE _canti FLOAT;
     DECLARE CONTINUE HANDLER FOR NOT FOUND SET doneLangLat = 1;

     REPEAT
     FETCH segunda INTO _ii,_canti;
     IF NOT doneLangLat THEN
        IF _rec = 1 THEN
            SET i = _canti * _cant;
            -- Insertamos
            INSERT INTO tm_inventario (id_ins,id_tipo_ope,id_cv,cant,fecha_r) 
            VALUES (_ii, 2, @id, i, _fecha);
        END IF;
     END IF;
     UNTIL doneLangLat END REPEAT;

  END block2;
  CLOSE segunda;

 END IF;

 UNTIL done END REPEAT;
 CLOSE primera;