通过多列化两列来在插入之前触发更新值

Question

我必须先用触发器修改插入数据的值。这是我的触发器：

DROP TRIGGER IF EXISTS `Calcul_conso`;CREATE DEFINER=`root`@`localhost` TRIGGER `Calcul_conso` BEFORE INSERT ON `data` FOR EACH ROW begin 
...
DECLARE multiplicateur FLOAT DEFAULT 1;
...

SELECT multiplicateur, calcul_conso into multiplicateur, c_c from capteur where sensor_number = NEW.sensor_number;

SET NEW.value = NEW.value * multiplicateur;
...
end

我有以下结构：

capteur

sensor_number（Primaire）varchar（64）非
nom varchar（150）Oui NULL
multiplicateur float Non 1

数据

id（Primaire）int（11）非
sensor_number varchar（64）非
value float Oui NULL
date datetime Non

我尝试了一个简单的*来繁殖，但似乎没有用。

示例：

new.value = 153265000和multiplicateur = 0.001

Answer 1

您的select语句看起来不对，您不应声明与列名同名的变量。

DROP TRIGGER IF EXISTS `Calcul_conso`;
delimiter $$
CREATE TRIGGER `Calcul_conso` BEFORE INSERT ON t 
FOR EACH ROW 
begin 

DECLARE vmultiplicateur FLOAT DEFAULT 1;

SELECT multiplicateur into vmultiplicateur from capteur where sensor_number = NEW.sensor_number;

SET NEW.value = NEW.value * vmultiplicateur;
end $$

delimiter ;

所以给出

drop table if exists capteur;
create table capteur
(sensor_number  varchar(64) ,
nom varchar(150) ,
multiplicateur float default 1
)
;

drop table if exists t;
create table t
(id int(11) ,
sensor_number varchar(64),
value float ,
date datetime);

insert into capteur values (1,'aaa',2);

insert into t values (1,1,10,'2018-01-01');

结果

ariaDB [sandbox]> select * from t;
+------+---------------+-------+---------------------+
| id   | sensor_number | value | date                |
+------+---------------+-------+---------------------+
|    1 | 1             |    20 | 2018-01-01 00:00:00 |
+------+---------------+-------+---------------------+
1 row in set (0.00 sec)