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How do you create a trigger in PostgreSQL?

How do you create a trigger in PostgreSQL?

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2024-09-10 last updatedFreePostgreSQL

To create a trigger in PostgreSQL, first define a function that performs the desired action. Then, use the `CREATE TRIGGER` statement to bind this function to a table event. For example: `CREATE FUNCTION log_update() RETURNS TRIGGER AS $$ BEGIN INSERT INTO log_table (table_name, changed_at) VALUES ('employees', CURRENT_TIMESTAMP); RETURN NEW; END; $$ LANGUAGE plpgsql;` and `CREATE TRIGGER trg_log_update AFTER UPDATE ON employees FOR EACH ROW EXECUTE FUNCTION log_update();`.

To create a trigger in PostgreSQL, first define a function that performs the desired action. Then, use the `CREATE TRIGGER` statement to bind this function to a table event. For example: `CREATE FUNCTION log_update() RETURNS TRIGGER AS $$ BEGIN INSERT INTO log_table (table_name, changed_at) VALUES ('employees', CURRENT_TIMESTAMP); RETURN NEW; END; $$ LANGUAGE plpgsql;` and `CREATE TRIGGER trg_log_update AFTER UPDATE ON employees FOR EACH ROW EXECUTE FUNCTION log_update();`.

To create a trigger in PostgreSQL, first define a function that performs the desired action. Then, use the `CREATE TRIGGER` statement to bind this function to a table event. For example: `CREATE FUNCTION log_update() RETURNS TRIGGER AS $$ BEGIN INSERT INTO log_table (table_name, changed_at) VALUES ('employees', CURRENT_TIMESTAMP); RETURN NEW; END; $$ LANGUAGE plpgsql;` and `CREATE TRIGGER trg_log_update AFTER UPDATE ON employees FOR EACH ROW EXECUTE FUNCTION log_update();`.

To create a trigger in PostgreSQL, first define a function that performs the desired action. Then, use the `CREATE TRIGGER` statement to bind this function to a table event. For example: `CREATE FUNCTION log_update() RETURNS TRIGGER AS $$ BEGIN INSERT INTO log_table (table_name, changed_at) VALUES ('employees', CURRENT_TIMESTAMP); RETURN NEW; END; $$ LANGUAGE plpgsql;` and `CREATE TRIGGER trg_log_update AFTER UPDATE ON employees FOR EACH ROW EXECUTE FUNCTION log_update();`.

How do you create a trigger in PostgreSQL?