MySQL SELECT DISTINCT和计数？
您需要将GROUPBY命令与MySQL的聚合函数count（*）结合使用才能实现。语法如下：
SELECT yourColumnName,COUNT(*) AS anyVariableNameFROM yourTableName GROUP BY yourColumnName;
为了理解上述语法，让我们创建一个表。创建表的查询如下：
mysql> create table selectDistinct_CountDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(10), -> AppearanceId int, -> PRIMARY KEY(Id) -> );
使用insert命令在表中插入一些记录。查询如下：
mysql> insert into selectDistinct_CountDemo(Name,AppearanceId) values('Larry',1);
mysql> insert into selectDistinct_CountDemo(Name,AppearanceId) values('John',2);
mysql> insert into selectDistinct_CountDemo(Name,AppearanceId) values('Larry',3);
mysql> insert into selectDistinct_CountDemo(Name,AppearanceId) values('Larry',10);
mysql> insert into selectDistinct_CountDemo(Name,AppearanceId) values('Carol',11);
mysql> insert into selectDistinct_CountDemo(Name,AppearanceId) values('Larry',15);使用select语句显示表中的所有记录。查询如下：
mysql> select *from selectDistinct_CountDemo;
以下是输出：
+----+-------+--------------+ | Id | Name | AppearanceId | +----+-------+--------------+ | 1 | Larry | 1 | | 2 | John | 2 | | 3 | Larry | 3 | | 4 | Larry | 10 | | 5 | Carol | 11 | | 6 | Larry | 15 | +----+-------+--------------+ 6 rows in set (0.00 sec)
这是选择不重复和计数的查询：
mysql> select Name,count(*) as TotalAppearance from selectDistinct_CountDemo -> group by Name;
以下是输出：
+-------+-----------------+ | Name | TotalAppearance | +-------+-----------------+ | Larry | 4 | | John | 1 | | Carol | 1 | +-------+-----------------+ 3 rows in set (0.00 sec)