插入、更新时的 MySql 触发器

Question

我已经使用 MySQL 一段时间了，但我对 MySQL 触发器完全陌生。

我有这个数据库:

• jours(jour (日期, 主键), ventes (int), soldeinitial( int)) ;
• achatscharges(Id (int, 主键), libelle (varchar), prix (int), #jour (date, forein键)。

在我的表('achatscharges')上每次插入或更新后，触发器应检查表'jours 中的'soldeinitial' 值' 为 null 然后用这个公式更新它:

'Something like( the value of 'jours.soldeinitial' of the last row in 'jours' - sum(achatscharges.prix) + jours.ventes'

这是我试过的:

CREATE TRIGGER UpdateSolde
AFTER INSERT, UPDATE ON achatscharges
FOR EACH ROW
BEGIN
IF((SELECT jours.soldeinitial FROM jours WHERE jours.jour=New.jour) IS NULL) 
THEN
UPDATE jours SET jours.soldeinitial=((SELECT jours.soldeinitial FROM jours WHERE jours.soldeinitial IS NOT NULL ORDER BY jours.jour DESC LIMIT 1)-SUM(New.prix)+jours.ventes) WHERE jours.jour=New.jour);
END IF;
END

这是例子:

+------------+-------- +---------------------+
| jour       | ventes  | soldeinitial        | 
+------------+---------+---------------------+
| 11-09-2017 | 1500    | 3000                |
| 12-09-2017 | 2000    | (must be calculated)|
| 13-09-2017 | 4000    | (must be calculated)|
+------------+---------+---------------------+
+------------+-------- +---------------------+
| id | libelle  | prix | #jour           |
+------------+---------+---------------------+
| 1  | somthing | 300  | 12-09-2017          |
| 2  | somthing | 200  | 12-09-2017          |
| 3  | somthing | 800  | 13-09-2017          |
+------------+---------+---------------------+
after triggger insert or update in achatscharges :
i should have this result :
+------------+-------- +---------------------------+
| jour       | ventes  | soldeinitial              | 
+------------+---------+---------------------------+
| 11-09-2017 | 1500    | 3000                      |
| 12-09-2017 | 2000    | 4500 =(3000-(300+500)+2000|
| 13-09-2017 | 4000    | 7700 =4500-(800)+4000     |
+------------+---------+---------------------------+

不好意思解释的不好，就是这个例子

+------------+-------- +-------------------------+
| jour       | ventes  | soldeinitial            | 
+------------+---------+-------------------------+
| 11-09-2017 | 1500    | 3000   manually         |
| 12-09-2017 | 2000    | 4500   calculated       |
| 13-09-2017 | 4000    | 7700   calculated       |
| 14-09-2017 | 3000    | *3000*   manually       |
| 15-09-2017 | 1500    | 3700 = *3000*-(800)+1500| the trigger doesn't work here the value still null
+------------+---------+-------------------------+
+------------+-------- +---------------------+
| id | libelle  | prix | #jour               |
+------------+---------+---------------------+
| 1  | somthing | 300  | 12-09-2017          |
| 2  | somthing | 200  | 12-09-2017          |
| 3  | somthing | 800  | 13-09-2017          |
| 4  | somthing | 800  | 15-09-2017          |
+------------+---------+---------------------+

希望澄清我注意到的内容。

Answer 1

我使用过这个测试数据:

CREATE TABLE jours
    (`jour` DATE, `ventes` int, `soldeinitial` int)
;
CREATE TABLE achatscharges
    (`id` int, `libelle` varchar(8), `prix` int, `jour` DATE)
;

INSERT INTO jours
    (`jour`, `ventes`, `soldeinitial`)
VALUES
    ('2017-09-11', 1500, 3000),
    ('2017-09-12', 2000, null),
    ('2017-09-13', 4000, null)
;

我创建了这样的插入触发器:

DELIMITER //
DROP TRIGGER IF EXISTS InsertSolde//
CREATE TRIGGER InsertSolde
AFTER INSERT ON achatscharges
FOR EACH ROW
BEGIN
DECLARE l_previous INTEGER;
DECLARE l_sumprix INTEGER;
IF EXISTS(SELECT jour FROM jours WHERE jour = NEW.jour) 
THEN
SET l_previous = (SELECT soldeinitial FROM jours WHERE soldeinitial IS NOT NULL AND jour < NEW.jour ORDER BY jour DESC LIMIT 1);
SET l_sumprix = (SELECT SUM(prix) FROM achatscharges WHERE jour = NEW.jour GROUP BY jour);
UPDATE jours SET soldeinitial = l_previous-l_sumprix+ventes WHERE jour=New.jour;
END IF;
END //
DELIMITER ;

并通过三个单一步骤对其进行了测试

INSERT INTO achatscharges
    (`id`, `libelle`, `prix`, `jour`)
VALUES
    (1, 'somthing', 300, '2017-09-12');

SELECT * FROM jours;    

INSERT INTO achatscharges
    (`id`, `libelle`, `prix`, `jour`)
VALUES
    (2, 'somthing', 200, '2017-09-12');

SELECT * FROM jours;    

INSERT INTO achatscharges
    (`id`, `libelle`, `prix`, `jour`)
VALUES
    (3, 'somthing', 800, '2017-09-13')
;
SELECT * FROM jours;    

希望对您有所帮助。更新触发器类似。