How can I make trigger to read from two separated attribute in two different tables and then
calculate something .
this is the code I want to make but the mysql says it has problem
CREATE TRIGGER `fee_calculate` BEFORE INSERT ON `BookingRoom`
FOR EACH ROW BEGIN
SET NEW.fee = `Booking.Night_Qty` * `Room.RoomPrice` ;
END
I Think It Should Help You
I made some assumptions:
I assumed you wanted to update the reorders table with a productID that matches the Products table. (you can do an insert but may run into PK issues depending on how you have your table set up).
I assumed that the reorder amount will be placed there.
I did NOT include transaction statements, I would recommend adding these so it's logged.
CREATE trigger updateprod
on Products
for update as
begin
declare #qtyonhand int,
#reorder int
if update(QtyonHand)
begin
select #qtyonhand = QtyonHand,#reorder = ReorderAmount from inserted
if #qtyonhand < #reorder
begin
update Reorders set ReorderAmount = #reorder, ReorderDate = getdate()
end
else if #qtyonhand >= #reorder
begin
delete from reorders where ProductID = ProductID
end
end
end
Related
I have the following snippet of an ER-diagram.
Whenever "order_item" is updated (i.e. when an item has been added to a 'shopping cart'), I want to decrement "Quantity" in the table "itemsinstock".
I know the syntax of a trigger (well, MySQL can also generate it) but I don't know how to do it. "order_item" needs to read ItemID from "itemsinstock" and based on that ID, it needs to decrement the quantity for that specific item. Is this possible?
Edit:
This is what I have now:
CREATE DEFINER=`root`#`localhost` TRIGGER
`orderdb`.`itemsinstock_AFTER_INSERT`
AFTER INSERT ON `order_item`
FOR EACH ROW
BEGIN UPDATE itemsinstock
SET Quantity = Quantity - order_item.itemQuantity WHERE itemID = ItemID; END
It gives me an error with "order_item.itemQuantity" .... It worked with "-1" but obviously I want it to decrement based on how many "itemQuantity" is. How do I do this?
Pretty close
CREATE DEFINER=`root`#`localhost` TRIGGER
`orderdb`.`itemsinstock_AFTER_INSERT`
AFTER INSERT ON `order_item`
FOR EACH ROW
BEGIN
UPDATE itemsinstock
SET Quantity = Quantity - NEW.itemQuantity WHERE itemID = NEW.id;
END
notice how order_item (which isn't defined) is being replaced by NEW which represents the row that was inserted. Also as a side note since this is a single statement you don't need begin end blocks
I have been trying to create a Trigger, however my attempts have been unsuccessful. I seem to be getting an error (#1064), which I have no solution for. Can somebody explain or demonstrate any faults in the syntax.
Let me specify:
I have delivery_id as primary key in delivery table,
I also have delivery_id as a foreign key in entry_log table.
By comparing both id's(if true), will return a text referring to the output of the bit (either 0 or 1)
DELIMITER //
DROP TRIGGER IF EXISTS entry_trigger//
CREATE TRIGGER entry_trigger BEFORE INSERT ON entry_log
FOR EACH ROW
BEGIN
DECLARE #xentry VARCHAR(45)
DECLARE #inta bit
SET #inta = SELECT allowed
FROM delivery
WHERE delivery.delivery_id = entry_log.delivery_id;
CASE
when #inta = 0 then #xentry = 'Acces Denied'
when #inta = 1 then #xentry = 'Acces Allowed'
END CASE
INSERT INTO entry_log(entry_time,access_allowed) VALUES(now(),#xentry);
END
//
This is assuming that you use MySQL. In the body of the trigger you use
WHERE delivery.delivery_id = entry_log.delivery_id;
I think you want to compare to the entry_log entry that the trigger is running on, right? In that case you must use this syntax:
WHERE delivery.delivery_id = NEW.delivery_id;
see here for more examples.
UPDATE
I see that also you try to do an INSERT INTO entry_log within the TRIGGER. This will of course not work, because you would create an infinite recursive loop. Within the
body of the trigger you can do unrelated table access, but not into the table you are inserting. You can change the values to be inserted by the trigger by setting NEW.xyz = whatever
UPDATE 2
I doubt, that your CASE statement is correct. At least it must end with END CASE. You can use IF here, since you don't have many cases to address. If you must use CASE this post might help you: MYSQL Trigger set datetime value using case statement
UPDATE 3
I am not sure, but I think you need brackets around the variable setting statement. try this trigger definition:
DELIMITER //
DROP TRIGGER IF EXISTS entry_trigger//
CREATE TRIGGER entry_trigger BEFORE INSERT ON entry_log
FOR EACH ROW
BEGIN
SET #inta = (SELECT allowed
FROM delivery
WHERE delivery.delivery_id = NEW.delivery_id);
SET NEW.access_allowed = #inta;
SET NEW.entry_time = NOW();
END
//
Note, that this is written out of my head, so beware of syntax errors in my script.
Well here is the problem...I want to update the inventory table at my database which includes
Sale(ProductID,Quantity,Price)
Invlevel(ProductID,Quantity)
I want to use triggers for this update. I have to use 2 triggers (I think). 1 at the sale tables which will be something like
CREATE TRIGGER `sale_AINS` AFTER INSERT ON sale FOR EACH ROW
begin
update Invlevel set quantity = Invlevel.quantity-"sale.quantity" where
Invlevel.ProductID = "sale.ProductID";
END
with this trigger, when a sale comes up, I want to adjust the inventory level at the product which the sale came to. However, even though this trigger has no errors and runs properly when I insert into sale table, it doesn't make any changes at the Invlevel table and I don't know why ( :# ).
Moreover, I made the trigger at the Invlevel table like that
CREATE TRIGGER `invlevel_AUPD` after UPDATE on invlevel FOR EACH ROW
if invlevel.quantity < 20
begin
insert into orders
(select productid,amount from reorder where reorder.productid = invlevel.productid )
end
*(orders,reorder are other tables)
It says to me I have syntax error which I don't know what it is and also even if I find it I can't even check the logic because the other trigger isn't even working... Any thought or help about it would be really helpful.
Try
First trigger
CREATE TRIGGER sale_AINS
AFTER INSERT ON sale
FOR EACH ROW
UPDATE invlevel
SET quantity = quantity - NEW.quantity
WHERE productid = NEW.productid;
In this trigger you don't need BEGIN END block since there is only one statement. In order to access column values or a row(s) that being inserted you need to use NEW keyword.
And the second one
DELIMITER $$
CREATE TRIGGER invlevel_AUPD
AFTER UPDATE ON invlevel
FOR EACH ROW
BEGIN
IF NEW.quantity < 20 THEN
INSERT INTO orders (productid, amount)
SELECT productid, amount
FROM reorder
WHERE productid = NEW.productid;
END IF;
END$$
DELIMITER ;
In the second trigger IF statement was out of BEGIN END block and syntax for IF was wrong. It should be IF ... THEN ... END IF;. And the same problems with a NEW keyword.
Here is SQLFiddle demo
You can put your IF condition into WHERE clause and make it more succinct like this
CREATE TRIGGER invlevel_AUPD
AFTER UPDATE ON invlevel
FOR EACH ROW
INSERT INTO orders (productid, amount)
SELECT productid, amount
FROM reorder
WHERE productid = NEW.productid
AND NEW.quantity < 20;
Here is updated SQLFiddle demo
I have an issue with a trigger on a mysql database. I have a table such as follows:
id int not null auto_increment (PK)
parent_id int not null,
rank int not null
What I'm trying to do is use a trigger to update the rank to the next highest +10 when they have the same parent_id, but this doesn't seem to be working.
DELIMITER $$
DROP TRIGGER IF EXISTS after_insert $$
create trigger after_insert
after insert on mytable
FOR EACH row
BEGIN
IF EXISTS (SELECT rank FROM mytable WHERE parent_id = new.parent_id AND id != new.id ORDER BY rank DESC LIMIT 1) THEN
UPDATE mytable SET rank = 10
WHERE id = new.id;
ELSE
UPDATE mytable SET rank = 20
WHERE id = new.id;
END IF;
END
$$
I've tried setting the new rank to a variable and calling the update statement using that, and again it didn't work. I even created another table to log what values were being selected and that worked perfectly so I can't quite understand what's going on. Is it a case of, although the trigger is "AFTER INSERT" the insert hasn't actually happened so it can't update the row it's just inserted? Another reason I ask this is, I've even tried updating the rank to different values e.g 1 and 2 depending on which statement it goes to, but it always ends up being 0.
I think you're on the right track with this thought:
Is it a case of, although the trigger is "AFTER INSERT" the insert hasn't actually happened so it can't update the row it's just inserted?
From the FAQ:
B.5.9: Can triggers access tables?
A trigger can access both old and new data in its own table. A trigger can also affect other tables, but it is not permitted to modify a table that is already being used (for reading or writing) by the statement that invoked the function or trigger.
The documentation isn't clear that what you're doing won't work. OTOH, the documentation isn't clear that what you're trying to do will work either.
I think you'd be better off using a BEFORE INSERT trigger and setting NEW.rank in there. Then, the new row would have the right rank value when it is actually inserted into the table rather than patching it after. Also, you'd be able to simplify your existence check to just this:
EXISTS(SELECT rank FROM mytable WHERE parent_id = new.parent_id)
as NEW.id wouldn't have a useful value and the new row wouldn't be in the table anyway; the ORDER BY and LIMIT are also unnecessary as you're just checking if something exists so I took them out.
A BEFORE INSERT trigger seems to match your intent better anyway and that will give you correct data as soon as it is inserted into your table.
If you want the rank to be set +10 more than highest "brother's" rank, you could use:
DELIMITER $$
DROP TRIGGER IF EXISTS whatever $$
create trigger whatever
BEFORE INSERT ON mytable
FOR EACH row
BEGIN
SET NEW.rank = 10 + COALESCE(
( SELECT max(rank)
FROM mytable
WHERE parent_id = NEW.parent_id
), 0 ) ;
END
$$
I have a trigger in which I want to have a variable that holds an INT I get from a SELECT, so I can use it in two IF statements instead of calling the SELECT twice. How do you declare/use variables in MySQL triggers?
You can declare local variables in MySQL triggers, with the DECLARE syntax.
Here's an example:
DROP TABLE IF EXISTS foo;
CREATE TABLE FOO (
i SERIAL PRIMARY KEY
);
DELIMITER //
DROP TRIGGER IF EXISTS bar //
CREATE TRIGGER bar AFTER INSERT ON foo
FOR EACH ROW BEGIN
DECLARE x INT;
SET x = NEW.i;
SET #a = x; -- set user variable outside trigger
END//
DELIMITER ;
SET #a = 0;
SELECT #a; -- returns 0
INSERT INTO foo () VALUES ();
SELECT #a; -- returns 1, the value it got during the trigger
When you assign a value to a variable, you must ensure that the query returns only a single value, not a set of rows or a set of columns. For instance, if your query returns a single value in practice, it's okay but as soon as it returns more than one row, you get "ERROR 1242: Subquery returns more than 1 row".
You can use LIMIT or MAX() to make sure that the local variable is set to a single value.
CREATE TRIGGER bar AFTER INSERT ON foo
FOR EACH ROW BEGIN
DECLARE x INT;
SET x = (SELECT age FROM users WHERE name = 'Bill');
-- ERROR 1242 if more than one row with 'Bill'
END//
CREATE TRIGGER bar AFTER INSERT ON foo
FOR EACH ROW BEGIN
DECLARE x INT;
SET x = (SELECT MAX(age) FROM users WHERE name = 'Bill');
-- OK even when more than one row with 'Bill'
END//
CREATE TRIGGER clearcamcdr AFTER INSERT ON `asteriskcdrdb`.`cdr`
FOR EACH ROW
BEGIN
SET #INC = (SELECT sip_inc FROM trunks LIMIT 1);
IF NEW.billsec >1 AND NEW.channel LIKE #INC
AND NEW.dstchannel NOT LIKE ""
THEN
insert into `asteriskcdrdb`.`filtre` (id_appel,date_appel,source,destinataire,duree,sens,commentaire,suivi)
values (NEW.id,NEW.calldate,NEW.src,NEW.dstchannel,NEW.billsec,"entrant","","");
END IF;
END$$
Dont try this # home
`CREATE TRIGGER `category_before_ins_tr` BEFORE INSERT ON `category`
FOR EACH ROW
BEGIN
**SET #tableId= (SELECT id FROM dummy LIMIT 1);**
END;`;
I'm posting this solution because I had a hard time finding what I needed. This post got me close enough (+1 for that thank you), and here is the final solution for rearranging column data before insert if the data matches a test.
Note: this is from a legacy project I inherited where:
The Unique Key is a composite of rridprefix + rrid
Before I took over there was no constraint preventing duplicate unique keys
We needed to combine two tables (one full of duplicates) into the main table which now has the constraint on the composite key (so merging fails because the gaining table won't allow the duplicates from the unclean table)
on duplicate key is less than ideal because the columns are too numerous and may change
Anyway, here is the trigger that puts any duplicate keys into a legacy column while allowing us to store the legacy, bad data (and not trigger the gaining tables composite, unique key).
BEGIN
-- prevent duplicate composite keys when merging in archive to main
SET #EXIST_COMPOSITE_KEY = (SELECT count(*) FROM patientrecords where rridprefix = NEW.rridprefix and rrid = NEW.rrid);
-- if the composite key to be introduced during merge exists, rearrange the data for insert
IF #EXIST_COMPOSITE_KEY > 0
THEN
-- set the incoming column data this way (if composite key exists)
-- the legacy duplicate rrid field will help us keep the bad data
SET NEW.legacyduperrid = NEW.rrid;
-- allow the following block to set the new rrid appropriately
SET NEW.rrid = null;
END IF;
-- legacy code tried set the rrid (race condition), now the db does it
SET NEW.rrid = (
SELECT if(NEW.rrid is null and NEW.legacyduperrid is null, IFNULL(MAX(rrid), 0) + 1, NEW.rrid)
FROM patientrecords
WHERE rridprefix = NEW.rridprefix
);
END
Or you can just include the SELECT statement in the SQL that's invoking the trigger, so its passed in as one of the columns in the trigger row(s). As long as you're certain it will infallibly return only one row (hence one value). (And, of course, it must not return a value that interacts with the logic in the trigger, but that's true in any case.)
As far I think I understood your question
I believe that u can simply declare your variable inside "DECLARE"
and then after the "begin" u can use 'select into " you variable" ' statement.
the code would look like this:
DECLARE
YourVar varchar(50);
begin
select ID into YourVar from table
where ...