2.8. Updates

You can update existing rows using the UPDATE command. Suppose you discover the temperature readings are all off by 2 degrees as of November 28. You may update the data as follows:

UPDATE weather
     SET temp_hi = temp_hi - 2,  temp_lo = temp_lo - 2
     WHERE date > '1994-11-28';

Look at the new state of the data:

SELECT * FROM weather;
 
      city      | temp_lo | temp_hi | prcp |    date
 ---------------+---------+---------+------+------------
  San Francisco |      46 |      50 | 0.25 | 1994-11-27
  San Francisco |      41 |      55 |    0 | 1994-11-29
  Hayward       |      35 |      52 |      | 1994-11-29
 (3 rows)