How to create a PostgreSQL trigger after an update?
I’m on my way of exploring triggers and want to create one that fires after an Update event on a game_saved column. As I have read in PostgreSQL docs it is possible to create triggers for columns. The column contains boolean values so the user may either add game to his collection or remove it.
Can a trigger be used to update a column?
We can also update this column using application, and we can also update this column using the user-defined function. But we can also create Trigger to perform this operation, and this automatic approach is good. Please visit other related articles…
How to auto update updated at in PostgreSQL?
So this is what you would need to. CREATE EXTENSION spi; ALTER TABLE users ALTER timestamp_at SET DEFAULT now (); DROP TRIGGER IF EXISTS update_users_updated_at ON users; CREATE TRIGGER mdt_users BEFORE UPDATE ON users FOR EACH ROW EXECUTE PROCEDURE moddatetime (timestamp_at); Not the answer you’re looking for?
Is there any way to pass the column name to the trigger?
My question is is there any way that I can pass the column name to the trigger and update the passed column, or is there is any other way that I am not aware of? moddatetime () is a trigger that stores the current time into a timestamp field. This can be useful for tracking the last modification time of a particular row within a table.
How does select and update work in PostgreSQL?
Without testing I claim this works: SELECT and UPDATE see the same snapshot of the database. The SELECT is bound to return the old values (even if you place the CTE after the CTE with the UPDATE ), while the UPDATE returns the new values by definition. Voilá.
Is it good idea to fire trigger after update of a specific column?
If I change AFTER UPDATE OF game_saved (column) to AFTER UPDATE ON game_info (table) the trigger works correctly. So there is some problem with creating a trigger specifically for a column update. Is it a good idea to fire the trigger on the column update or should I look for another approach here?
What does the optional returning Clause do in PostgreSQL?
The optional RETURNING clause causes UPDATE to compute and return value (s) based on each row actually updated. Any expression using the table’s columns, and/or columns of other tables mentioned in FROM, can be computed. The new (post-update) values of the table’s columns are used.