在MySQL中先显示不为空值的结果,然后再显示为空值的结果
让我们首先创建一个表-
create table DemoTable1357-> (
-> StudentName varchar(40),
-> StudentCountryName varchar(30)
-> );
使用插入命令在表中插入一些记录-
insert into DemoTable1357 values('Chris','US');insert into DemoTable1357 values('David',NULL);
insert into DemoTable1357 values('David','AUS');
insert into DemoTable1357 values('Carol',NULL);
insert into DemoTable1357 values('Mike','UK');
使用select语句显示表中的所有记录-
select * from DemoTable1357;
这将产生以下输出-
+-------------+--------------------+| StudentName | StudentCountryName |
+-------------+--------------------+
| Chris | US |
| David | NULL |
| David | AUS |
| Carol | NULL |
| Mike | UK |
+-------------+--------------------+
5 rows in set (0.00 sec)
以下是查询以首先显示不为空值然后为空值的结果-
select * from DemoTable1357-> order by (StudentCountryName IS NULL),StudentName;
这将产生以下输出-
+-------------+--------------------+| StudentName | StudentCountryName |
+-------------+--------------------+
| Chris | US |
| David | AUS |
| Mike | UK |
| Carol | NULL |
| David | NULL |
+-------------+--------------------+
5 rows in set (0.00 sec)
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