Updates the column values for the rows that match a predicate. When no predicate is provided, update the column values for all rows.
UPDATE events SET eventType = 'click' WHERE eventType = 'clk'
UPDATE supports subqueries in the
WHERE clause, including
NOT EXISTS, and scalar subqueries.
UPDATE all_events SET session_time = 0, ignored = true WHERE session_time < (SELECT min(session_time) FROM good_events) UPDATE orders AS t1 SET order_status = 'returned' WHERE EXISTS (SELECT oid FROM returned_orders WHERE t1.oid = oid) UPDATE events SET category = 'undefined' WHERE category NOT IN (SELECT category FROM events2 WHERE date > '2001-01-01')
The following types of subqueries are not supported:
- Nested subqueries, that is, a subquery inside another subquery
NOT INsubquery inside an
OR, for example,
a = 3 OR b NOT IN (SELECT c from t)
In most cases, you can rewrite
NOT IN subqueries using
NOT EXISTS. We recommend using
NOT EXISTS whenever possible, as
NOT IN subqueries can be slow.