触发器创建及Navicat中使用

　　mysql中的触发器（trigger）使用

　Trigger：

　　示例：

mysql> CREATE TABLE account (acct_num INT, amount DECIMAL(10,2));
Query OK, 0 rows affected (0.03 sec)

mysql> CREATE TRIGGER ins_sum BEFORE INSERT ON account
-> FOR EACH ROW SET @sum = @sum + NEW.amount;
Query OK, 0 rows affected (0.06 sec)

　　

　　解析：<原谅我这懒惰的搬运工>

　　　

　　　The

CREATE TRIGGER

statement creates a trigger named

ins_sum

that is associated with the

account

table. It also includes clauses that specify the trigger action time, the triggering event, and what to do when the trigger activates:

The keyword

BEFORE

indicates the trigger action time. In this case, the trigger activates before each row inserted into the table. The other permitted keyword here is

AFTER

.

The keyword

INSERT

indicates the trigger event; that is, the type of operation that activates the trigger. In the example,

INSERT

operations cause trigger activation. You can also create triggers for

DELETE

and

UPDATE

operations.

The statement following

FOR EACH ROW

defines the trigger body; that is, the statement to execute each time the trigger activates, which occurs once for each row affected by the triggering event. In the example, the trigger body is a simple

SET

that accumulates into a user variable the values inserted into the

amount

column. The statement refers to the column as

NEW.amount

which means “the value of the

amount

column to be inserted into the new row.”

　　具体参见：http://dev.mysql.com/doc/refman/5.7/en/trigger-syntax.html

　　Navicat中使用

　　1.选中要添加触发器的表；

　　 2.打开其设计表；

　　 3.打开触发器，在指定栏中设置触发器；

　　　

　　　具体参见：http://blog.csdn.net/cqnuztq/article/details/9735245