I am struggling to understand the format to create an 'insert before' trigger that must meet conditions of other tables.
For example, if I have a table named 'borrowed' that I would like to insert values into but must meet conditions from another table called 'member'. The condition is that MemberStatus = 'regular'. If this condition passes, I will be able to run a 'insert into borrowed' but if the conditions aren't met then it will not be able to pass.
This is how I previously understood the concept but after hours of reading i've become confused. Any help would be appreciated.
delimiter //
drop trigger if exists trigger1
//
create trigger trigger1
before insert on borrowed
for each row
begin
if...
end if;
end;
//
Related
Thank you for your help.
I have 3 tables on MySQL. One Table for my users and second is for my user features, the third one is for roles. First of all, I need to add registration on a measures table when the user is inserted. I mean if I add a new user to tbl_users the trigger will grab the user id and write on the tbl_measures that's it. I need just this.
INSERT INTO tbl_measures (user_id) VALUES (tbl_users.id)
this my triggers it is working partly. when I add a new user trigger add a new line to tbl_measures without id.
When you refer NEW.id in your insert trigger, there are two main cases. In the first case you get the proper id value. This is what you expect. In the second case it's null. This is what happens.
Essential is whether the trigger runs before or after the insert. Before the insert the id does not exist, because the record was not created yet. After the insert the id exists. Long story short code:
DELIMITER //
CREATE TRIGGER PROOFOFCONCEPT
AFTER INSERT
ON EACH ROW
BEGIN
INSERT INTO tbl_measures(user_id)
VALUES (NEW.id);
END; //
DELIMITER ;
I found the solution:
CREATE TRIGGER `after_members_insert` AFTER INSERT ON `tbl_users`
FOR EACH ROW BEGIN
INSERT INTO tbl_measures(user_id)
VALUES(new.id);
END
I have several tables in the database: Users, Profiles, Articles
I also have one table called Changes, which is used for administrative purposes. This table consists of id, table_name, and date_created.
What I need to do is whenever something is added, deleted or updated in a regular table (Users, Profiles, Articles), create a new row in the Changes with the name of the updated table and the current timestamps.
I've been browsing for a while and tried many different methods, but nothing really worked. I know the solution should be very simple, may be someone can help me. Thank you for your time.
So in this case you need 9 trigger 3 for each of the regular table after insert, after update, after delete
Here is for one table you can write for the others
When you insert on Users
delimiter //
create trigger log_user_insert after insert on Users
for each row
begin
insert into Changes (table_name,date_created) values ('Users',now());
end; //
delimiter ;
When update happens on Users
delimiter //
create trigger log_user_update after update on Users
for each row
begin
insert into Changes (table_name,date_created) values ('Users',now());
end; //
delimiter ;
When delete happens on Users
delimiter //
create trigger log_user_update after delete on Users
for each row
begin
insert into Changes (table_name,date_created) values ('Users',now());
end; //
delimiter ;
I would suggest to add a column called action in the table Changes and to insert each action name as well i.e. insert,update and delete.
You need to create an update, insert and delete trigger on each of the data tables:
CREATE TRIGGER upd_changes_users BEFORE UPDATE ON Users
FOR EACH ROW
BEGIN
INSERT INTO changes (table_name, date_created) VALUES ('users', NOW());
END;
This code assumes, that the id column in changes is auto_generated. You might also want to consider including a type column in the changes table (to differentiate between insert, update and delete).
I am trying to write a MySQL trigger. I have two tables that look like this:
When a customer makes a purchase a new record is added to each table. I have added column ‘sku_copy’ to Table B, so it does not get populated when a new record is created.
When a new record is created, I want my trigger to copy the ‘sku’ field in Table A to the ‘sku_copy’ field in Table B. However, the problem I am having is how to structure the following condition in the trigger.
IF: ‘order_id’ in Table A matches ‘order_id’ in Table B. THEN: copy ‘sku’ from that Table A record to the record in Table B with the matching ‘order_id’. The data should be added to Table B ‘sku_copy'.
ELSE: don’t do anything.
Can someone show me how to write this into my trigger?
Thanks for any help you can give.
Try this but why do u think of using trigger for this ?
DELIMITER $$
CREATE TRIGGER trigger_name
AFTER INSERT ON tableA
FOR EACH ROW BEGIN
INSERT INTO tableB
SET sku_copy = OLD.sku,
order_id = OLD.order_id,
order = OLD.order;
END$$
DELIMITER ;
I want to post the trigger that was constructed with examples offered here and on another forum. Thanks to everyone who helped with this.
DELIMITER $$
CREATE TRIGGER sku_AfterInsert
AFTER INSERT ON uau3h_virtuemart_order_items
FOR EACH ROW BEGIN
UPDATE uau3h_virtuemart_orders
SET order_item_sku_copy = NEW.order_item_sku
WHERE virtuemart_order_id = NEW.virtuemart_order_id;
END$$;
DELIMITER ;
This is my create triggers . I want when Insert vhftofass it execute this query(UPDATE vhf_msg_rx SET msg_text="";) that means Its make Null this table vhf_msg_rx.But when i write that query after insert Query it make error (Can't update table 'vhf_msg_rx' in stored function/trigger because it is already used by statement which invoked this stored function/trigger.) Please help me how can i do this
CREATE
/*!50017 DEFINER = 'root'#'localhost' */
TRIGGER `VHFtoFASS` AFTER UPDATE ON `vhf_msg_rx`
FOR EACH ROW BEGIN
INSERT INTO vhftofass SELECT NULL,msg_text,NOW(),0 FROM vhf_msg_rx WHERE msg_text<>"";
END;
$$
I'm not completely clear on what you're trying to do, but it seems like you want to copy modified rows of one table into another, but only retaining certain fields. You could do that by referencing the inserted record with NEW.columnname inside the FOR EACH ROW loop, for example
CREATE TRIGGER `VHFtoFASS` AFTER UPDATE ON `vhf_msg_rx`
FOR EACH ROW BEGIN
INSERT INTO vhftofass VALUES(NULL,NEW.msg_text,NOW(), 0);
END;
Note that this will only handle updates - you'll need an INSERT trigger to capture new rows.
DELIMITER $$
CREATE TRIGGER stock_empty AFTER UPDATE on products
FOR EACH ROW
DELETE FROM products WHERE stock <=0;
END$$
I am trying to make my products table check itself after every UPDATE statement and delete rows that have 0 or negative stock counts. I could manage to get this far, but it is not working.
Thanks for any help
If it's that easy, how come you didn't solve it yourself?
DELIMITER ||
CREATE TRIGGER stock_empty AFTER UPDATE on products
FOR EACH ROW BEGIN
DELETE FROM products WHERE stock <=0;
END ||
[edit]
That's how correct syntax should look like, however there's one more thing:
A stored function or trigger cannot
modify a table that is already being
used (for reading or writing) by the
statement that invoked the function or
trigger.
From: http://dev.mysql.com/doc/refman/5.5/en/stored-program-restrictions.html