MariaDB 10.4

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SELECT VERSION();


VERSION()


10.4.26-MariaDB-1:10.4.26+maria~deb10-log


CREATE TABLE `tblpagos` (
  `idPago` INT(11) NOT NULL,
  `pagoValor` INT(11) NOT NULL,
  `pagoPrestamoId` INT(11) NOT NULL
);
CREATE TABLE `tblprestamos` (
  `idPrestamo` INT(11) NOT NULL,
  `capital` INT(11) NOT NULL,
  `interes` INT(11) NOT NULL,
  `estado` INT(11) NOT NULL
);
CREATE TRIGGER `t_UpdateEstadoPrestamo1` AFTER INSERT ON `tblpagos`
FOR EACH ROW
BEGIN
  DECLARE `totalimporte` DOUBLE;
  DECLARE `totalpagos` DOUBLE;

  SET `totalimporte` := (
    SELECT `p`.`capital` + `p`.`interes`
    FROM `tblprestamos` `p`
    WHERE `p`.`idPrestamo` =  NEW.`pagoPrestamoId`
  );
  SET `totalpagos` := (
    SELECT SUM(
      CASE WHEN `pagoPrestamoId` = NEW.`pagoPrestamoId` THEN `pagoValor`
      ELSE 0
      END
    )
    FROM `tblpagos`
  );

  IF (`totalimporte` = `totalpagos`) THEN
    UPDATE `tblprestamos`
    SET `estado` = 3
    WHERE `idPrestamo` = NEW.`pagoPrestamoId`;
  END IF;
END;
INSERT INTO `tblprestamos` (
  `idPrestamo`,
  `capital`,
  `interes`,
  `estado`
) VALUES
  (1, 500000, 50000, 1),
  (2, 200000, 20000, 1);

Records: 2  Duplicates: 0  Warnings: 0


INSERT INTO `tblpagos` (
  `idPago`,
  `pagoValor`,
  `pagoPrestamoId`
) VALUES
  (1, 25000, 1),
  (2, 10000, 1),
  (1, 25000, 1);

Records: 3  Duplicates: 0  Warnings: 0


SELECT
  `idPrestamo`,
  `capital`,
  `interes`,
  `estado`
FROM
  `tblprestamos`;


idPrestamo
capital
interes
estado


1
500000
50000
1

2
200000
20000
1


SELECT
  `idPago`,
  `pagoValor`,
  `pagoPrestamoId`
FROM
  `tblpagos`;


idPago
pagoValor
pagoPrestamoId


1
25000
1

2
10000
1

1
25000
1