How to prevent insert in MySQL under certain conditions?
This causes the statement that spawned the trigger to be aborted. Create your ‘before insert’ trigger to check for a condition and disallow. You inserted a blank string, the trigger saw it was blank and raised the signal to prevent the insert. Example 2, MySQL, Cancel the insert in the trigger by causing the data to violate a not null constraint.
Is there a way to ignore the insert in MySQL?
Alternatively, look at the MERGE statement. You can also use INSERT IGNORE which silently ignores the insert instead of updating or inserting a row when you have a unique index on (user, item). The query will look like this: You can add the unique index with CREATE UNIQUE INDEX user_item ON x_table (user, item).
How to do a conditional update in MySQL?
DELIMITER // DROP PROCEDURE `GetFlavour`// CREATE PROCEDURE `GetFlavour` (`FlavourID` INT, `FlavourName` VARCHAR (20)) BEGIN IF EXISTS (SELECT * FROM Flavours WHERE ID = FlavourID) THEN UPDATE Flavours SET ID = FlavourID; ELSE INSERT INTO Flavours (ID, Name) VALUES (FlavourID, FlavourName); END IF; END // DELIMITER ; You could use this code.
How to create trigger to prevent insert in MySQL?
Create your ‘before insert’ trigger to check for a condition and disallow. You inserted a blank string, the trigger saw it was blank and raised the signal to prevent the insert. Example 2, MySQL, Cancel the insert in the trigger by causing the data to violate a not null constraint.
What is the BEFORE INSERT clause in MySQL?
Second, use BEFORE INSERT clause to specify the time to invoke the trigger. Third, specify the name of the table that the trigger is associated with after the ON keyword. Finally, specify the trigger body which contains one or more SQL statements that execute when the trigger is invoked.
How to create a trigger if condition exists in MySQL?
DROP TRIGGER IF EXISTS upd_user; DELIMITER $$ CREATE TRIGGER upd_user BEFORE UPDATE ON `user` FOR EACH ROW BEGIN IF (NEW.password IS NULL OR NEW.password = ”) THEN SET NEW.password = OLD.password; ELSE SET NEW.password = Password (NEW.Password); END IF; END$$ DELIMITER ; However, this means a user can never blank out a password.