MySQL触发器插入，更新

Question

I have been using MySQL for some time but I am totally new to MySQL triggers.

I have this database :

• jours ( jour (date, primary key), ventes (int), soldeinitial( int)) ;
• achatscharges ( Id (int, primary key), libelle (varchar), prix (int), #jour (date, forein key).

After each INSERT OR UPDATE on my table (' achatscharges ') the trigger should check if ' soldeinitial ' value in table ' jours ' is null then update it with this formula :

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

This is what I have tried :

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

This is example :

+------------+-------- +---------------------+
| 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     |
+------------+---------+---------------------------+

excuse me to not explain very well,this is the example

+------------+-------- +-------------------------+
| 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          |
+------------+---------+---------------------+

Hope that clarify what I noted.

Answer 1

I've worked with this testdata:

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)
;

I've created the insert trigger like this:

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 ;

And tested it with three single steps

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;    

Hope that helps. An update trigger is similar.