MySQL查询仅更新单个字段代替NULL
为此，您可以使用COALESCE()。让我们首先创建一个表-
mysql> create table DemoTable1805
(
Name1 varchar(20),
Name2 varchar(20)
);使用插入命令在表中插入一些记录-
mysql> insert into DemoTable1805 values('Chris',NULL);
mysql> insert into DemoTable1805 values('David','Mike');
mysql> insert into DemoTable1805 values(NULL,'Mike');使用select语句显示表中的所有记录-
mysql> select * from DemoTable1805;
这将产生以下输出-
+-------+-------+ | Name1 | Name2 | +-------+-------+ | Chris | NULL | | David | Mike | | NULL | Mike | +-------+-------+ 3 rows in set (0.00 sec
这是仅更新一个字段的查询-
mysql> update DemoTable1805
set Name1 = coalesce(Name1,Name2);
Rows matched: 3 Changed: 1 Warnings: 0让我们再次检查表记录-
mysql> select * from DemoTable1805;
这将产生以下输出-
+-------+-------+ | Name1 | Name2 | +-------+-------+ | Chris | NULL | | David | Mike | | Mike | Mike | +-------+-------+ 3 rows in set (0.00 sec)