假设如果一个表中有许多值在表的列中包含空格，那么这是浪费空间。我们可以使用 trim() 函数从所有行中删除空格并在单个查询中更新表。按照“employee”的示例，所有行中都有空格将展示这一概念 -
示例mysql> select * from employee;+------+----------------------+----------------------+----------------------+| id | name | address | department |+------+----------------------+----------------------+----------------------+| 100 | raman | delhi | it || 101 | mohan | haryana | history || 102 | shyam | chandigarh | english || 103 | sukhjeet singh | patiala | computer engg. || 104 | bimal roy | calcutta | computer engg. | +------+----------------------+----------------------+----------------------+5 rows in set (0.00 sec)
从上面的结果集中我们可以看到，employee 表的行中有很多空格。可以使用以下查询删除和更新它 -
mysql> update employee set id = trim(id), name = trim(name), address = trim(address), department = trim(department);query ok, 5 rows affected (0.24 sec)rows matched: 5 changed: 5 warnings: 0mysql> select * from employee;+------+----------------+------------+----------------+| id | name | address | department |+------+----------------+------------+----------------+| 100 | raman | delhi | it || 101 | mohan | haryana | history || 102 | shyam | chandigarh | english || 103 | sukhjeet singh | patiala | computer engg. || 104 | bimal roy | calcutta | computer engg. |+------+----------------+------------+----------------+5 rows in set (0.00 sec)
从上面的结果集中可以看到，所有的空格都被删除了，表格也被更新了。
以上就是我们如何使用 mysql trim() 删除所有行中的空格并更新表？的详细内容。