SELECT <myColumnSpec> = CASE WHEN <A> THEN <somethingA> WHEN <B> THEN <somethingB> ELSE <somethingE> END 1. 在上面的代码中需要用具体的参数代替尖括号中的内容。下面是一个简单的例子: USE pubs GO SELECT Title, 'Price Range' = CASE WHEN price IS NULL THEN 'Unpriced' WHEN price < 10...
You may find theMySQL User Forumshelpful when working with triggers. For answers to commonly asked questions regarding triggers in MySQL, seeSection A.5, “MySQL 8.0 FAQ: Triggers”. There are some restrictions on the use of triggers; seeSection 27.8, “Restrictions on Stored Programs”. ...
I would like to know if can i insert,update or delete data into replicated table using a trigger. For example: When i insert data into Table_A on master server, automatically the same data is inserted into Table_A of my slave server, but when i use a trigger to insert data into Tabl...
OK, let's talk about the code. Using the CREATE TRIGGER statement, we've initiated the trigger, naming it 'sales_bi_trg'. MySQL triggers can fire before or after an INSERT, UPDATE or DELETE event. This one fires before any data is inserted in the 'sales' table. The FOR EACH ROW c...
you can also change its value withSET NEW.col_name=valueif you have theUPDATEprivilege for it. This means you can use a trigger to modify the values to be inserted into a new row or used to update a row. (Such aSETstatement has no effect in anAFTERtrigger because the row change wil...
When a trigger is activated (by a user who has privileges to execute INSERT, UPDATE, or DELETE statements for the table associated with the trigger), trigger execution requires that the user who defined the trigger still have the TRIGGER privilege. ...
Temporary tables.CREATE TEMPORARY TABLEandDROP TEMPORARY TABLEstatements are not supported insidetransactions, procedures, functions, and triggers when using GTIDs (that is, when theenforce_gtid_consistencysystem variable is set toON). It is possible to use these statements with GTIDs enabled, but ...
报错2:Error Code: 1442. Can't update table 'student' in stored function/trigger because it is already used by statement which invoked this stored function/trigger. 原因:存储的函数或触发器不能修改已被调用该函数或触发器的语句(用于读取或写入)使用的表。
Description:When I use the trigger and procedure with the same name, I get an error "can't reopen table" while calling the procedure. The procedure performs DELETE from the table using JOIN with a temporary table. It's enough to rename the trigger and the problem disappears.How to repeat...
Triggers cannot useNEW.col_nameor useOLD.col_nameto refer to generated columns. For information about generated columns, seeSection 15.1.20.8, “CREATE TABLE and Generated Columns”. MySQL stores thesql_modesystem variable setting in effect when a trigger is created, and always executes the trig...