忽略MySQL中的空值并显示其余值
使用ISNOTNULL查找非空值并显示它们。让我们首先创建一个表-
mysql> create table DemoTable1458 -> ( -> StudentName varchar(20), -> StudentScore int -> );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable1458 values('Chris Brown',56);
mysql> insert into DemoTable1458 values('David Miller',NULL);
mysql> insert into DemoTable1458 values('John Doe',78);
mysql> insert into DemoTable1458 values('Adam Smith',NULL);使用select语句显示表中的所有记录-
mysql> select * from DemoTable1458;
这将产生以下输出-
+--------------+--------------+ | StudentName | StudentScore | +--------------+--------------+ | Chris Brown | 56 | | David Miller | NULL | | John Doe | 78 | | Adam Smith | NULL | +--------------+--------------+ 4 rows in set (0.00 sec)
这是忽略空值的查询-
mysql> select StudentName,StudentScore from DemoTable1458 -> where StudentScore IS NOT NULL;
这将产生以下输出-
+-------------+--------------+ | StudentName | StudentScore | +-------------+--------------+ | Chris Brown | 56 | | John Doe | 78 | +-------------+--------------+ 2 rows in set (0.00 sec)