Postgresql 中文操作指南

2.9. Deletions #

可以使用 DELETE 命令从表中删除行。假设您不再关心海沃德的天气情况。然后，您可以执行以下操作从表中删除这些行：

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';

删除属于海沃德的所有天气记录。

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)

人们应该警惕以下形式的语句

One should be wary of statements of the form

DELETE FROM tablename;

如果没有限定符，DELETE 将从给定的表格中移除 all 行，留下一个空表格。系统不会在执行此操作之前请求确认！

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