PostgeSQL Update Query

UPDATE changes the values of the specified columns in all rows that meet the condition.

Syntax

[ WITH [ RECURSIVE ] with_query [, ...] ]
UPDATE [ ONLY ] table_name [ * ] [ [ AS ] alias ]
    SET { column_name = { expression | DEFAULT } |
          ( column_name [, ...] ) = ( { expression | DEFAULT } [, ...] ) |
          ( column_name [, ...] ) = ( sub-SELECT )
        } [, ...]
    [ FROM from_item [, ...] ]
    [ WHERE condition | WHERE CURRENT OF cursor_name ]
    [ RETURNING * | output_expression [ [ AS ] output_name ] [, ...] ]

Example

Update the column capacity of the table flights:

UPDATE
    flights
SET
    capacity = 300
WHERE
    code = 'UA5502'
AND date = '2009-02-03';

--

UPDATE
    flights
SET
    capacity = DEFAULT
WHERE
    code = 'UA5502'
AND date = '2009-02-03';

--

UPDATE
    flights
SET
    capacity = capacity + 1
WHERE
    code = 'UA5502'
AND date = '2009-02-03';

Update the table flights using the table logs’s information:

UPDATE
    flights
SET
    capacity = DEFAULT
FROM
    logs
WHERE
    logs.event = 'Arrival'
AND flights.date = '2009-02-03';

--

UPDATE
    flights
SET
    capacity = DEFAULT
WHERE
    date = (
    SELECT
        date
     FROM
        logs
     WHERE
        log.event = 'Arrival'
     AND log.id = 55021
    );

References:

• https://www.postgresql.org/docs/9.5/sql-update.html