Mysql - The trigger do not update my database - mysql

Question

this is my trigger :
--
-- Déclencheurs `reservation`
--
DROP TRIGGER IF EXISTS `UpdateFactureOnInsert`;
DELIMITER //
CREATE TRIGGER `UpdateFactureOnInsert` AFTER INSERT ON `reservation`
FOR EACH ROW BEGIN
DECLARE quota, montant, tarif INT;
DECLARE nombreHeure INT DEFAULT (SELECT COUNT(heure.numero) FROM heure WHERE heure.code = NEW.code);
DECLARE mois INT DEFAULT (SELECT heure.mois FROM heure WHERE heure.code = NEW.code LIMIT 1);
DECLARE annee INT DEFAULT (SELECT heure.annee FROM heure WHERE heure.code = NEW.code LIMIT 1);
DECLARE identifiant INT DEFAULT (SELECT facture.identifiant FROM facture WHERE facture.association = NEW.association
AND facture.mois = mois
AND facture.annee = annee LIMIT 1);
IF (identifiant = null) THEN
SET identifiant = ((SELECT MAX(facture.identifiant) FROM facture) +1);
INSERT INTO facture (facture.association, facture.annee, facture.mois, facture.identifiant, facture.quota, facture.montant)
VALUES (NEW.association, annee, mois, identifiant, 20, 0);
END IF;
SET quota = (SELECT facture.quota FROM facture WHERE facture.identifiant = identifiant
AND facture.association = NEW.association
AND facture.mois = mois
AND facture.annee = annee);
SET montant = (SELECT facture.montant FROM facture WHERE facture.identifiant = identifiant
AND facture.association = NEW.association
AND facture.mois = mois
AND facture.annee = annee);
IF (nombreHeure >= quota) THEN
SET quota = quota - nombreHeure;
ELSE
SET tarif = (SELECT salle.tarif FROM salle WHERE salle.numero = NEW.numero);
SET montant = montant + (nombreHeure - quota) * tarif;
SET quota = 0;
END IF;
UPDATE facture SET facture.quota = quota, facture.montant = montant WHERE facture.association = NEW.association
AND facture.mois = mois
AND facture.annee = annee
AND facture.identifiant = identifiant;
END
//
DELIMITER ;
Those are my:
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SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
SET time_zone = "+00:00";
/*!40101 SET #OLD_CHARACTER_SET_CLIENT=##CHARACTER_SET_CLIENT */;
/*!40101 SET #OLD_CHARACTER_SET_RESULTS=##CHARACTER_SET_RESULTS */;
/*!40101 SET #OLD_COLLATION_CONNECTION=##COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
--
-- Base de données: `reserv`
--
CREATE DATABASE IF NOT EXISTS `reserv` DEFAULT CHARACTER SET latin1 COLLATE latin1_swedish_ci;
USE `reserv`;
-- --------------------------------------------------------
--
-- Structure de la table `association`
--
CREATE TABLE IF NOT EXISTS `association` (
`association` int(11) NOT NULL AUTO_INCREMENT,
`libelle` char(32) NOT NULL,
PRIMARY KEY (`association`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=6 ;
-- --------------------------------------------------------
--
-- Structure de la table `facture`
--
CREATE TABLE IF NOT EXISTS `facture` (
`association` int(11) NOT NULL,
`annee` int(11) NOT NULL,
`mois` int(11) NOT NULL,
`identifiant` int(11) NOT NULL,
`quota` int(11) NOT NULL,
`montant` int(11) NOT NULL,
PRIMARY KEY (`association`,`mois`,`annee`,`identifiant`),
KEY `i_fk_facture_mois` (`mois`,`annee`),
KEY `i_fk_facture_association` (`association`),
KEY `facture_ibfk_1` (`annee`,`mois`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
-- --------------------------------------------------------
--
-- Structure de la table `heure`
--
CREATE TABLE IF NOT EXISTS `heure` (
`numero` int(11) NOT NULL,
`association` int(11) NOT NULL,
`code` int(11) NOT NULL,
`annee` int(11) NOT NULL,
`mois` int(11) NOT NULL,
`jour` int(11) NOT NULL,
`heure` int(11) NOT NULL,
PRIMARY KEY (`numero`,`association`,`code`,`annee`,`mois`,`jour`,`heure`),
KEY `i_fk_heure_mois` (`annee`,`mois`),
KEY `i_fk_heure_reservation` (`numero`,`association`,`code`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
-- --------------------------------------------------------
--
-- Structure de la table `mois`
--
CREATE TABLE IF NOT EXISTS `mois` (
`mois` int(11) NOT NULL,
`annee` int(11) NOT NULL,
PRIMARY KEY (`annee`,`mois`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
-- --------------------------------------------------------
--
-- Structure de la table `reservation`
--
CREATE TABLE IF NOT EXISTS `reservation` (
`numero` int(11) NOT NULL,
`association` int(11) NOT NULL,
`code` int(11) NOT NULL,
PRIMARY KEY (`numero`,`association`,`code`),
KEY `i_fk_reservation_association` (`association`),
KEY `i_fk_reservation_salle` (`numero`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
-- --------------------------------------------------------
--
-- Structure de la table `salle`
--
CREATE TABLE IF NOT EXISTS `salle` (
`numero` int(11) NOT NULL AUTO_INCREMENT,
`capacite` int(11) NOT NULL,
`tarif` int(11) NOT NULL,
PRIMARY KEY (`numero`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=5 ;
--
-- Contraintes pour les tables exportées
--
--
-- Contraintes pour la table `facture`
--
ALTER TABLE `facture`
ADD CONSTRAINT `facture_ibfk_1` FOREIGN KEY (`annee`, `mois`) REFERENCES `mois` (`annee`, `mois`),
ADD CONSTRAINT `facture_ibfk_2` FOREIGN KEY (`association`) REFERENCES `association` (`association`);
--
-- Contraintes pour la table `reservation`
--
ALTER TABLE `reservation`
ADD CONSTRAINT `reservation_ibfk_1` FOREIGN KEY (`association`) REFERENCES `association` (`association`),
ADD CONSTRAINT `reservation_ibfk_2` FOREIGN KEY (`numero`) REFERENCES `salle` (`numero`);
/*!40101 SET CHARACTER_SET_CLIENT=#OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=#OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=#OLD_COLLATION_CONNECTION */;
Just please tell me how can I fix it, because the trigger doesn't work properly.

Answer 1

One issue I see is that this conditional test:
IF (identifiant = null)
Will never return TRUE. If you want to test whether a variable is set to the NULL value, use the IS NULL operator.
IF (identifiant IS NULL)
I've never used a query as the DEFAULT value for a variable. (That may be valid, I've just never seen it done that way before.)
I'd code it like this:
DECLARE nombreHeure INT;
SELECT COUNT(heure.numero) INTO nombreHeure
FROM heure
WHERE heure.code = NEW.code;
Any place you are assigning the result from a query into a variable, you need to ensure that the query doesn't return more than one row. The query above will return a single row (assuming, that is, it doesn't throw an error), so it's okay.
For a lot of the other queries in your trigger it's not clear (to the casual reader) that these will return only one row.
Another big problem looks like you are local variables have the same name as columns in SQL statements. MySQL isn't going to see that as a reference to a variable, it's going to see it as a reference to a column. (When MySQL encounters a identifier in a SQL statement, it first checks to see if it's a column, only when it can't find a column of that name does it consider that it might be a variable.)
For example:
AND facture.mois = mois
For the reference to mois on the right side, MySQL first looks for a column named that in one of the tables (from any row source in scope), before it looks at it as a variable. In this case, it's going to find mois as a column in facture, so that SQL is basically equivalent to:
AND facture.mois = fracture.mois
which is effectively the same as:
AND facture.mois IS NOT NULL
Basically, you need to ensure that the variable names used in SELECT statements are distinct from all column names in tables referenced by the query.