This is a continuation of this question: Insert data into a table with a foreign key SQL
I need to create a trigger that updates a counter variable after I insert a row into a table. The counter variable keeps track of how many new rows are inserted into the ItemBook table. However, after running the script, the trigger doesn't seem to be working. Also how can I reuse this trigger if I have created it already?
CREATE TABLE count (
countBook INT DEFAULT 0 NOT NULL,
);
CREATE
TRIGGER count_trigger AFTER INSERT
ON ItemBook
FOR EACH ROW
UPDATE count
SET countBook = (SELECT COUNT(*) FROM Itembook)
INSERT INTO Item
VALUES('Clippers','amazon.com', 'hair clippers');
SET SQL_SAFE_UPDATES = 0;
INSERT INTO ItemBook
VALUES('Clippers','Bob')
SET SQL_SAFE_UPDATES = 1;
SELECT * FROM count;
The countBook column returns nothing after running the script. Furthermore, if I try to rerun this script again it will say Trigger already exists (after creating it). How do I reuse this trigger?
The trigger would look something like this:
CREATE TRIGGER count_trigger AFTER INSERT ON ItemBook
FOR EACH ROW
BEGIN
UPDATE count
SET countBook = countBook + 1;
END;
It seems very curious to have a table with one row for this information. But this appear to be what you are trying to do.
Related
I have an after insert trigger that is supposed to update the field total in my table "test" where the id_cart is equal to new.id_cart. However my trigger is updating every single row in the table not only the one desired. I would like to know how can I modify my trigger so it only updates the row that I want.
This is my trigger.
CREATE DEFINER=`root`#`localhost` TRIGGER `update_total_test`
AFTER INSERT ON `test_product_quantity_cart`
FOR EACH ROW BEGIN
UPDATE test set total= (select sum(price_product) from test_product_quantity_cart where id_cart=new.id_cart);
END
So if the new row inserted in table "test_product_quantity_cart" has an new.id_cart=1, then only the row in table "test" with id_cart=1 should be uptated.
I think I am missing a "where" clause to indicate the update statement which rows it is suppossed to upate. However I do not know how to add that clause.
Thank you!
CREATE DEFINER=`root`#`localhost` TRIGGER `update_total_test`
AFTER INSERT ON `test_product_quantity_cart`
FOR EACH ROW
UPDATE test
JOIN ( SELECT id_cart, SUM(price_product) total
FROM test_product_quantity_cart
WHERE id_cart=NEW.id_cart ) value_for_update USING (id_cart)
SET test.total = value_for_update.total;
In my schema I had two columns ,I am new to MySQL how to concatenate columns using Computed Column in mysql
ordertbl schema
Autoorderid int auto-increment
Orderid varchar(45)
I want to value orderid value insert when new row inserted
i had created the trigger for but this trigger is not firing when i am inserting the row
insert into order_master(customerID,ItemID,quantity,Unitprice,Total) values ('07961A','1000',6,5,30)
use ntc_sales; DELIMITER
$$ CREATE TRIGGER order_master_BINS BEFORE INSERT ON order_master FOR EACH ROW
SET NEW.OrderID = CONCAT('ORD' ,NEW.AutoOrderID) ; end;
create table
enter code here
CREATE TABLE Demo(ID INT PRIMARY KEY,
IDwithChar AS 'ORD' + RIGHT('0000000' + CAST(ID AS VARCHAR(10)), 6) PERSISTED,valuevar nvarchar(45)
)
This is showing syntax error in mysql how to create table as above schema in mysql
You can't really do this using a trigger in MySQL.
A BEFORE trigger is run before the auto increment value is set, so NEW.AutoOrderID will always be 0.
An AFTER trigger cannot update the same table as it is triggered on.
In other words, instead of triggering on an INSERT, creating the row using a stored procedure that does the insert/update in a single transaction is probably the best way to proceed.
EDIT: You could use a separate table for the sequence, but that would not guarantee that the order number is the same value as AutoOrderID, just a unique value.
CREATE TABLE order_sequence (
seq INT PRIMARY KEY AUTO_INCREMENT
);
CREATE TRIGGER order_master_BINS BEFORE INSERT ON order_master
FOR EACH ROW
BEGIN
INSERT INTO order_sequence VALUES (0);
SET NEW.OrderID = CONCAT('ORD', LAST_INSERT_ID());
END
An SQLfiddle to test the alternate solution with.
MySql trigger is very interesting, but very tricky.
I have some problem, I want to run a trigger once after insert on .
I want to run my trigger once after rows inserted, is there anything like for each table``???
how to make this trigger run only once, but not for each row created.
CREATE
DEFINER=`root`#`localhost`
TRIGGER `mydb`.`leave_taken_trigger`
AFTER INSERT ON `mydb`.`leave`
FOR EACH ROW
BEGIN
set #lt:= (SELECT count(*) FROM `leave` where (staff_leave_application_staff_id_staff = new.staff_leave_application_staff_id_staff and leave_type_id_leave_type = new.leave_type_id_leave_type) and active = 1 );
INSERT INTO `leave_taken`(leave_type_id_leave_type, staff_id_staff, taken_days, updated)
VALUES (new.leave_type_id_leave_type, new.staff_leave_application_staff_id_staff, IFNULL(#lt,0), CURDATE())
ON DUPLICATE KEY UPDATE taken_days=IFNULL(#lt,0), updated = CURDATE();
END$$
I think you can't achieve your requirement with trigger.
Your trigger will run in every row created.
I suggest you to using stored procedure from your code after the INSERT has successfully completed.
I am currently in the process of writing my first trigger in MySQL within PHPmyadmin. I would like it so that when an item in one table is updated, a row in another table is inserted. Several columns of the row that is to be inserted in the second table are determined by the values being updated in the first table.
Therefore, I need to INSERT a new row in table B when an update occurs on table A. And some of the values of the columns in table B are to be defined by the values in the updated table A row which caused the trigger to run.
Please find the trigger below.
CREATE TRIGGER `before_categoryiteminstance_update` BEFORE UPDATE ON `TABLEA`
FOR EACH ROW BEGIN
declare f_guidcategoryiteminstance int;
declare f_guidcategory int;
INSERT INTO TABLEB
SET
f_guidcategoryiteminstance =(SELECT guidcategoryiteminstance FROM inserted),
f_guidcategory =(SELECT guidcategory FROM inserted),
guiduser= f_guidcategory,
guidcategoryinstance= f_guidcategoryiteminstance,
number= number +1,
dateofaction= NOW(); END
The trigger can be added to the DB fine. However, when I attempt to update a row on table A (which should cause the trigger to run), I get an error stating that the table Inserted does not exist. However, I was under the impression that Inserted should be a logical table that contains the results of the initial part of the trigger. Is this only the case if the trigger is being run on an insert and not an update? If so, is there an equivalent for an update trigger?
I am new to DB development. Please help me create a trigger for moving data from one table to another.
I have two tables, one contains "Transaction Status" from where I want to move records on transaction status change into another table having completed transactions. So the value in one table will get deleted and will get inserted into another table.
Please correct me in the following trigger:
create trigger transaction_state after update on test_archive for each row begin
insert into test_me(select * from test_archive where new.Transaction_status = 2);
delete from test_archive where new.Transaction_status = 2;
end;
Why do I feel like I am helping you with homework? Your trigger, as written, will probably move ALL rows when someone updates a row to Transaction_Status=2. Since you didn't join the NEW table to the test_archive table, your WHERE clauses will be true for all rows.
if you really want all rows with Transaction_status=2 moved from test_archive to test_me, then get rid of the FOR EACH and the references to the NEW table.
create trigger transaction_state after update on test_archive
begin
insert into test_me
select * from test_archive where Transaction_status = 2;
delete from test_archive where Transaction_status = 2;
end;