What is mutating table error?
A mutating table error (ORA-04091) occurs when a row-level trigger tries to examine or change a table that is already undergoing change (via an INSERT, UPDATE, or DELETE statement). In particular, this error occurs when a row-level trigger attempts to read or write the table from which the trigger was fired.
Can we use two triggers on same table before after update?
yes you can create more than one triggers on same table.
How many triggers you can have on a table?
There are 12 types of triggers can exist in a table in Oracle: 3 before statement, 3 after statement, 3 before each row and 3 after each row. On a single table you can define as many triggers as you need.
How do you prevent a mutating error in a trigger?
Don’t use triggers – The best way to avoid the mutating table error is not to use triggers. While the object-oriented Oracle provides “methods” that are associated with tables, most savvy PL/SQL developers avoid triggers unless absolutely necessary.
How to create triggers that update the same table?
I have just started using triggers and one thing that I would need to do is to create a trigger that updates the same table that’s inserting the row.
Can You update the same table in MySQL?
However, I can’t update the same table: Can’t update table ACCOUNTS already used by the statement that invoked this trigger
How to create Trigger after update in MySQL?
CREATE TRIGGER upd_total_votes AFTER UPDATE ON products_score FOR EACH ROW UPDATE products_score SET products_score.votes_total = (SELECT (votes_1 + votes_2 + votes_3 + votes_4 + votes_5) FROM products_score WHERE id = new.id)
How to create trigger to update country before insert?
DELIMITER $$ CREATE TRIGGER `populate_country_id` BEFORE INSERT ON `city` FOR EACH ROW BEGIN IF NEW.country_id = 0 THEN UPDATE city INNER JOIN country B ON city.country = B.country SET NEW.country_id = B.country_id; END IF; END $$ DELIMITER ;