业务情景：有这样一张表：其中Id列为表主键，Name为用户名，State为记录的状态值，Note为状态的说明，方便阅读。

需求描述：需要查询出这样的结果：某个人某种状态的记录数，如：张三，待审核记录数，审核中记录数，审核通过记录数；大概像这样：

解决方案：

1.建表和初始化测试数据：

--1.建表语句

CREATE TABLE [dbo].[Content]

(

	[Id] [int] NULL,

	[Name]   [nvarchar](50) NULL,

	[State]  [int] NULL,

	[Note]   [nvarchar](50) NULL,

)

GO

--2.初始化数据

INSERT INTO CONTENT VALUES(1,'张三',1,'待审核')

INSERT INTO CONTENT VALUES(2,'张三',2,'审核中')

INSERT INTO CONTENT VALUES(3,'张三',2,'审核中')

INSERT INTO CONTENT VALUES(4,'李四',1,'待审核')

INSERT INTO CONTENT VALUES(5,'李四',2,'审核中')

INSERT INTO CONTENT VALUES(5,'李四',3,'审核通过')</span>

2.查询语句：

SELECT NAME,

       SUM(审核通过) AS '审核通过',

       SUM(待审核) AS '待审核',

       SUM(审核中) AS '审核中'

FROM   (

           (

               SELECT NAME,

                      COUNT(*) AS '审核通过',

                      0 AS '审核中',

                      0 AS '待审核'

               FROM   CONTENT

               WHERE  [STATE] = 3

                      AND NAME IN ('张三', '李四')

               GROUP BY

                      NAME

           ) 

           UNION 

           (

               SELECT NAME,

                      0 AS '审核通过',

                      COUNT(*) AS '审核中',

                      0 AS '待审核'

               FROM   CONTENT

               WHERE  [STATE] = 2

                      AND NAME IN ('张三', '李四')

               GROUP BY

                      NAME

           )

           UNION

           (

               SELECT NAME,

                      0 AS '审核通过',

                      0 AS '审核中',

                      COUNT(*) AS '待审核'

               FROM   CONTENT

               WHERE  [STATE] = 1

                      AND NAME IN ('张三', '李四')

               GROUP BY

                      NAME

           )

       )temp

GROUP BY

       NAME</span>

这里用到两个知识点：

1.UNION 操作符用于合并两个或多个 SELECT 语句的结果集。请注意，UNION 内部的 SELECT 语句必须拥有相同数量的列。列也必须拥有相似的数据类型。同时，每条 SELECT 语句中的列的顺序必须相同。

2.GROUP BY + 聚合函数(如SUM, COUNT, MAX, AVG等)统计数据。