http://jackxiang.com/index.php zh-cn http://jackxiang.com/post// jack <xdy108@126.com> Tue, 31 Jan 2012 08:18:43 +0000 http://jackxiang.com/post// 实例一：
select coalesce(null,"carrot","apple");
返回结果：carrot
mysql> select coalesce(null,"carrot","apple");
+---------------------------------+
| coalesce(null,"carrot","apple") |
+---------------------------------+
| carrot                          |
+---------------------------------+
实例二：
select coalesce(1,"carrot","apple")
返回结果：1
友情提示：coalesce里的参数如果是字符串的话，务必用单引号或者双引号廓起来；
这些语句可以直接在mysql里运行。
mysql> select coalesce(1,"carrot","apple");
+------------------------------+
| coalesce(1,"carrot","apple") |
+------------------------------+
| 1                            |
+------------------------------+
1 row in set (0.00 sec)
实际用到在查询时有可能是null时，显示0，如下 ：
mysql> select coalesce(null, 0);  
+-------------------+
| coalesce(null, 0) |
+-------------------+
| 0                 |
+-------------------+
1 row in set (0.00 sec)

mysql> select coalesce('1', 0);
+------------------+
| coalesce('1', 0) |
+------------------+
| 1                |
+------------------+
1 row in set (0.00 sec) ]]> http://jackxiang.com/post//#blogcomment <user@domain.com> Thu, 01 Jan 1970 00:00:00 +0000 http://jackxiang.com/post//#blogcomment