Before insert trigger behavior in mysql - mysql

I created a table with some data in it, and a trigger like this:
DROP TRIGGER IF EXISTS verifica_cpf;
DELIMITER //
CREATE TRIGGER verifica_cpf
BEFORE INSERT ON `usuario` FOR EACH ROW
BEGIN
IF (SELECT COUNT(*) FROM usuario WHERE cpf = new.cpf) > 1 THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'CPF EXISTENTE!';
END IF;
END//
DELIMITER ;
Basically it checks for duplicate 'cpf' values before inserts.
Let's say that in my table, there's one entry with this cpf value: 873.255.218-12
If i try to insert another entry with the same cpf value, the trigger won't work. But if i insert it again, it will.
How can i solve this?


You can change this by changing the 1 to 0:
DROP TRIGGER IF EXISTS verifica_cpf;
DELIMITER //
CREATE TRIGGER verifica_cpf
BEFORE INSERT ON `usuario` FOR EACH ROW
BEGIN
IF (SELECT COUNT(*) FROM usuario WHERE cpf = new.cpf) > 0 THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'CPF EXISTENTE!';
END IF;
END//
DELIMITER ;
Or by using the more efficient if exists:
DROP TRIGGER IF EXISTS verifica_cpf;
DELIMITER //
CREATE TRIGGER verifica_cpf
BEFORE INSERT ON `usuario` FOR EACH ROW
BEGIN
IF exists (SELECT 1 FROM usuario WHERE cpf = new.cpf) THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'CPF EXISTENTE!';
END IF;
END//
DELIMITER ;

Related

Creating trigger to prevent insert with condition from other table

im trying to create trigger that prevent insert on buku_dalam_pinjam with certain condition from other table which is anggota_dosen. this is my current trigger
CREATE DEFINER=`root`#`localhost` TRIGGER `buku_dalam_pinjam_BI`
BEFORE INSERT ON `buku_dalam_pinjam`
FOR EACH ROW BEGIN
if (buku_dalam_pinjam.id_agt_dosen=anggota_dosen.id_agt_dosen and
anggota_dosen.ttl_proses_pinjam >=5) then
signal sqlstate '45000' set message_text="error message";
end if;
END
it was succesfully created, then when i try to insert data on buku_dalam_pinjam
it gave me error message, but when i erase the trigger it let me insert on buku_dalam_pinjam table. so is there any mistake in my trigger?
anggota_dosen table
buku_dalam_pinjam table
error message when i include the trigger

try this
drop trigger if exists buku_dalam_pinjam_BI;
delimiter $$
CREATE TRIGGER `buku_dalam_pinjam_BI`
BEFORE INSERT ON buku_dalam_pinjam
FOR EACH ROW BEGIN
if exists (select 1 from anggota_dosen
where new.id_agt_dosen = anggota_dosen.id_agt_dosen and
anggota_dosen.ttl_proses_pinjam >=5) then
signal sqlstate '45000' set message_text="error message";
end if;
END $$
delimiter ;

MySQL "create trigger tr_emp before insert or update"

delimiter //
create trigger tr_emp2 before insert or update
on employee for each row
begin
if new.ID<>10100 then
if new.Mgr not in (select ID from employee)
then
SIGNAL SQLSTATE '45000'
SET MESSAGE_TEXT = 'Invalid Mgr_id!';
end if;
end if;
end;//
delimiter ;
How to express "create trigger tr_emp before insert or update" ,is it a wrong exoression ?

You have to create two triggers, but you can move the common code into a procedure and have them both call the procedure.

How to create MySQL trigger

I have table users with two fields id (numeric) and email (with full email adress) how to add trigger which can prevent adding new email records with specific domains eg: *#somedomain.com?

The trigger would look like this:
DELIMITER $$
CREATE TRIGGER USER_INSERT BEFORE INSERT ON USER
FOR EACH ROW
BEGIN
IF new.email like '%#somedomain.com' THEN
SIGNAL sqlstate '99999'
SET message_text = 'Invalid domain';
END IF;
END$$
DELIMITER ;

Please try this:
DELIMITER $$
CREATE TRIGGER example_before_insert_reject_domains
BEFORE INSERT ON example_tbl FOR EACH ROW
BEGIN
IF NEW.email LIKE '%#somedomain.com'
THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE_TEXT = 'Cannot add or update row: invalid domain for email';
END IF;
END;
$$

MySQL: condition between two columns

I have two columns:
commission (percental('yes','no'))
recurring(enum('yes','no').
I want to declare the following dependency:
recurring can only be 'yes', when percental is 'yes', too.
Is there a possibility to manage it within mysql?

you could create two triggers to check for this, sqlfiddle
CREATE
TRIGGER `before_insert` BEFORE INSERT
ON `commission`
FOR EACH ROW BEGIN
IF NEW.recurring = 'yes' AND NEW.percental != 'yes' THEN
signal sqlstate '45000' set message_text = "percental must be 'yes' for recurring to be 'yes'";
END IF;
END/
CREATE
TRIGGER `before_update` BEFORE UPDATE
ON `commission`
FOR EACH ROW BEGIN
IF NEW.recurring = 'yes' AND NEW.percental != 'yes' THEN
signal sqlstate '45000' set message_text = "percental must be 'yes' for recurring to be 'yes'";
END IF;
END/
since the code is the same for UPDATE and INSERT you might want to create a procedure to call for both triggers like this sqlfiddle
DROP PROCEDURE IF EXISTS check_commission_recurring_based_on_percental/
CREATE PROCEDURE check_commission_recurring_based_on_percental(IN percental ENUM('yes','no'), IN recurring ENUM('yes','no'))
BEGIN
IF recurring = 'yes' AND percental != 'yes' THEN
signal sqlstate '45000' set message_text = "percental must be 'yes' for recurring to be 'yes'";
END IF;
END/
CREATE
TRIGGER `before_insert` BEFORE INSERT
ON `commission`
FOR EACH ROW BEGIN
CALL check_commission_recurring_based_on_percental(NEW.percental,NEW.recurring);
END/
CREATE
TRIGGER `before_update` BEFORE UPDATE
ON `commission`
FOR EACH ROW BEGIN
CALL check_commission_recurring_based_on_percental(NEW.percental,NEW.recurring);
END/

Mysql triggers with multiple values

How can i do the same with username value in one trigger?
Thanks
DELIMITER //
CREATE TRIGGER notnullnameandsurname BEFORE INSERT ON guests FOR EACH ROW
BEGIN
IF new.name = "" then
SIGNAL SQLSTATE '45000';
END IF;
END //

How about using or?
DELIMITER //
CREATE TRIGGER notnullnameandsurname BEFORE INSERT ON guests FOR EACH ROW
BEGIN
IF new.name = '' or new.username = '' then
SIGNAL SQLSTATE '45000';
END IF;
END //