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。
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