2.9. Deletions #

Rows can be removed from a table using the DELETE command. Suppose you are no longer interested in the weather of Hayward. Then you can do the following to delete those rows from the table:

 DELETE FROM weather WHERE city = 'Hayward'; 

All weather records belonging to Hayward are removed.

 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 (2 rows) 

One should be wary of statements of the form

 DELETE FROM tablename; 

Without a qualification, DELETE will remove all rows from the given table, leaving it empty. The system will not request confirmation before doing this!

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