我可以使用MySQL获取列中重复值的计数吗？
是的，您可以将ORDERBYDESC与GROUPBY一起使用。让我们首先创建一个表-
create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> PostMessage varchar(100) -> );
使用插入命令在表中插入一些记录-
insert into DemoTable(PostMessage) values('Hi');
insert into DemoTable(PostMessage) values('Hello');
insert into DemoTable(PostMessage) values('Hi');
insert into DemoTable(PostMessage) values('Awesome');
insert into DemoTable(PostMessage) values('Hello');
insert into DemoTable(PostMessage) values('Hi');
insert into DemoTable(PostMessage) values('Awesome');使用select语句显示表中的所有记录-
select *from DemoTable;
输出结果
这将产生以下输出-
+----+-------------+ | Id | PostMessage | +----+-------------+ | 1 | Hi | | 2 | Hello | | 3 | Hi | | 4 | Awesome | | 5 | Hello | | 6 | Hi | | 7 | Awesome | +----+-------------+ 7 rows in set (0.00 sec)
以下是查询以获取MySQL数据库中最大的值-
select PostMessage,count(Id) from DemoTable group by PostMessage
-> order by count(Id) DESC;输出结果
这将产生以下输出-
+-------------+-----------+ | PostMessage | count(Id) | +-------------+-----------+ | Hi | 3 | | Hello | 2 | | Awesome | 2 | +-------------+-----------+ 3 rows in set (0.00 sec)
如果只想要最高，则可以使用以下查询-
select PostMessage,count(Id) from DemoTable group by PostMessage having count(Id) > 2;
输出结果
这将产生以下输出-
+-------------+-----------+ | PostMessage | count(Id) | +-------------+-----------+ | Hi | 3 | +-------------+-----------+ 1 row in set (0.00 sec)