Trigger for Duplicate rows (Please help)
Im creating an employee database for TAFE. I have an employee table with employee_id and place fields.
The trigger is activated by the Before Insert event.
When there's a duplication of employee_id and place the trigger generates a message. For example if a new inserted row has employee_id 20 place 6, and there is a row with employee_id 20 and place 6 already existed in the Employee table, the trigger generates a message: Duplicate Employee_id 20 Place 6.
I don't want a unique constraint.
The code is below:
Im having syntax problem in MYSQL. What could be wrong?
CREATE TRIGGER employee_tg ON employee
BEFORE INSERT ON employee
FOR EACH ROW
IF NOT EXISTS (SELECT 1 FROM employee e
INNER JOIN INSERTED i
INSERT INTO employee(employee_id,place)
RAISEERROR ('Duplicate employee_id 20 Place 6)
Any help would be appreciated!