显示和连接记录，忽略MySQL中的NULL值
使用CONCAT()来连接记录，而IFNULL()以检查NULL值。
让我们首先创建一个表-
mysql> create table DemoTable802 ( FirstName varchar(100), LastName varchar(100) );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable802 values('Adam','Smith');
mysql> insert into DemoTable802 values('Carol',NULL);
mysql> insert into DemoTable802 values(NULL,'Taylor');
mysql> insert into DemoTable802 values(NULL,NULL);使用select语句显示表中的所有记录-
mysql> select *from DemoTable802;
这将产生以下输出-
+-----------+----------+ | FirstName | LastName | +-----------+----------+ | Adam | Smith | | Carol | NULL | | NULL | Taylor | | NULL | NULL | +-----------+----------+ 4 rows in set (0.00 sec)
以下是连接记录而忽略NULL值的查询-
mysql> select concat(IFNULL(FirstName,''),' ',IFNULL(LastName,'')) AS FULL_NAME from DemoTable802;
这将产生以下输出-
+------------+ | FULL_NAME | +------------+ | Adam Smith | | Carol | | Taylor | | | +------------+ 4 rows in set (0.00 sec)