表如下
id varchar(50) 主键
UserName varchar(50)
舒张压 int
收缩压 int
测量日期 datetime
录入日期 datetime default(getdate())内容如下id username 舒张压 收缩压 测量日期 录入日期
1 zhang 120 90 2009-1-1 2009-1-1 11:22:33
2 li 120 85 2009-1-2 2009-1-2 12:22:22
3 ming 130 89 2009-1-3 2009-1-3 23:22:33
4 zhang 129 100 2009-2-3 2009-2-3 22:22:22
5 zhang 120 100 2009-2-4 2009-2-4 12:20:38
6 li 110 82 2009-2-4 2009-2-4 22:12:22
7 ming 140 100 2009-2-4 2009-2-4 11:10:22每个人都有多条记录,得到每个人最新的那条记录结果这样
5 zhang 120 100 2009-2-4 2009-2-4 12:20:38
6 li 110 82 2009-2-4 2009-2-4 22:12:22
7 ming 140 100 2009-2-4 2009-2-4 11:10:22
id varchar(50) 主键
UserName varchar(50)
舒张压 int
收缩压 int
测量日期 datetime
录入日期 datetime default(getdate())内容如下id username 舒张压 收缩压 测量日期 录入日期
1 zhang 120 90 2009-1-1 2009-1-1 11:22:33
2 li 120 85 2009-1-2 2009-1-2 12:22:22
3 ming 130 89 2009-1-3 2009-1-3 23:22:33
4 zhang 129 100 2009-2-3 2009-2-3 22:22:22
5 zhang 120 100 2009-2-4 2009-2-4 12:20:38
6 li 110 82 2009-2-4 2009-2-4 22:12:22
7 ming 140 100 2009-2-4 2009-2-4 11:10:22每个人都有多条记录,得到每个人最新的那条记录结果这样
5 zhang 120 100 2009-2-4 2009-2-4 12:20:38
6 li 110 82 2009-2-4 2009-2-4 22:12:22
7 ming 140 100 2009-2-4 2009-2-4 11:10:22
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-- Author: liangCK 小梁
-- Title : 查每个分组前N条记录
-- Date : 2008-11-13 17:19:23
---------------------------------
--> 生成测试数据: #T
IF OBJECT_ID('tempdb.dbo.#T') IS NOT NULL DROP TABLE #T
CREATE TABLE #T (ID VARCHAR(3),GID INT,Author VARCHAR(29),Title VARCHAR(39),Date DATETIME)
INSERT INTO #T
SELECT '001',1,'邹建','深入浅出SQLServer2005开发管理与应用实例','2008-05-10' UNION ALL
SELECT '002',1,'胡百敬','SQLServer2005性能调校','2008-03-22' UNION ALL
SELECT '003',1,'格罗夫Groff.J.R.','SQL完全手册','2009-07-01' UNION ALL
SELECT '004',1,'KalenDelaney','SQLServer2005技术内幕存储引擎','2008-08-01' UNION ALL
SELECT '005',2,'Alex.Kriegel.Boris.M.Trukhnov','SQL宝典','2007-10-05' UNION ALL
SELECT '006',2,'飞思科技产品研发中心','SQLServer2000高级管理与开发','2007-09-10' UNION ALL
SELECT '007',2,'胡百敬','SQLServer2005数据库开发详解','2008-06-15' UNION ALL
SELECT '008',3,'陈浩奎','SQLServer2000存储过程与XML编程','2005-09-01' UNION ALL
SELECT '009',3,'赵松涛','SQLServer2005系统管理实录','2008-10-01' UNION ALL
SELECT '010',3,'黄占涛','SQL技术手册','2006-01-01'--SQL查询如下:--按GID分组,查每个分组中Date最新的前2条记录
--1.字段ID唯一时:
SELECT * FROM #T AS T WHERE ID IN(SELECT TOP 2 ID FROM #T WHERE GID=T.GID ORDER BY Date DESC)--2.如果ID不唯一时:
SELECT * FROM #T AS T WHERE 2>(SELECT COUNT(*) FROM #T WHERE GID=T.GID AND Date>T.Date)--SQL Server 2005 使用新方法--3.使用ROW_NUMBER()进行排位分组
SELECT ID,GID,Author,Title,Date
FROM
(
SELECT rid=ROW_NUMBER() OVER(PARTITION BY GID ORDER BY Date DESC),*
FROM #T
) AS T
WHERE rid<=2--4.使用APPLY
SELECT DISTINCT b.*
FROM #T AS a
CROSS APPLY
(
SELECT TOP(2) * FROM #T WHERE a.GID=GID ORDER BY Date DESC
) AS b
--结果
/*ID GID Author Title Date
---- ----------- ----------------------------- --------------------------------------- -----------------------
003 1 格罗夫Groff.J.R. SQL完全手册 2009-07-01 00:00:00.000
004 1 KalenDelaney SQLServer2005技术内幕存储引擎 2008-08-01 00:00:00.000
005 2 Alex.Kriegel.Boris.M.Trukhnov SQL宝典 2007-10-05 00:00:00.000
007 2 胡百敬 SQLServer2005数据库开发详解 2008-06-15 00:00:00.000
009 3 赵松涛 SQLServer2005系统管理实录 2008-10-01 00:00:00.000
010 3 黄占涛 SQL技术手册 2006-01-01 00:00:00.000(6 行受影响)
*/
if object_id('[tb]') is not null drop table [tb]
go
create table [tb]([id] int,[username] varchar(5),[舒张压] int,[收缩压] int,[测量日期] varchar(10),[录入日期] datetime)
insert [tb]
select 1,'zhang',120,90,'2009-1-1','2009-1-1 11:22:33' union all
select 2,'li',120,85,'2009-1-2','2009-1-2 12:22:22' union all
select 3,'ming',130,89,'2009-1-3','2009-1-3 23:22:33' union all
select 4,'zhang',129,100,'2009-2-3','2009-2-3 22:22:22' union all
select 5,'zhang',120,100,'2009-2-4','2009-2-4 12:20:38' union all
select 6,'li',110,82,'2009-2-4','2009-2-4 22:12:22' union all
select 7,'ming',140,100,'2009-2-4','2009-2-4 11:10:22'
---查询---
select * from tb t
where not exists(select * from tb where username=t.username and 录入日期>t.录入日期)---结果---
id username 舒张压 收缩压 测量日期 录入日期
----------- -------- ----------- ----------- ---------- ------------------------------------------------------
5 zhang 120 100 2009-2-4 2009-02-04 12:20:38.000
6 li 110 82 2009-2-4 2009-02-04 22:12:22.000
7 ming 140 100 2009-2-4 2009-02-04 11:10:22.000(所影响的行数为 3 行)
-- Author: liangCK 小梁
---------------------------------
--> 生成测试数据: @T
DECLARE @T TABLE (id INT,username VARCHAR(5),舒张压 INT,收缩压 INT,测量日期 DATETIME,录入日期 DATETIME)
INSERT INTO @T
SELECT 1,'zhang',120,90,'2009-1-1','2009-1-1 11:22:33' UNION ALL
SELECT 2,'li',120,85,'2009-1-2','2009-1-2 12:22:22' UNION ALL
SELECT 3,'ming',130,89,'2009-1-3','2009-1-3 23:22:33' UNION ALL
SELECT 4,'zhang',129,100,'2009-2-3','2009-2-3 22:22:22' UNION ALL
SELECT 5,'zhang',120,100,'2009-2-4','2009-2-4 12:20:38' UNION ALL
SELECT 6,'li',110,82,'2009-2-4','2009-2-4 22:12:22' UNION ALL
SELECT 7,'ming',140,100,'2009-2-4','2009-2-4 11:10:22'--SQL查询如下:SELECT * FROM @T AS T WHERE ID IN(SELECT TOP 1 ID FROM @T WHERE username=T.username ORDER BY 录入日期 DESC)
/*
id username 舒张压 收缩压 测量日期 录入日期
----------- -------- ----------- ----------- ----------------------- -----------------------
5 zhang 120 100 2009-02-04 00:00:00.000 2009-02-04 12:20:38.000
6 li 110 82 2009-02-04 00:00:00.000 2009-02-04 22:12:22.000
7 ming 140 100 2009-02-04 00:00:00.000 2009-02-04 11:10:22.000(3 行受影响)
*/
if object_id('[tb]') is not null drop table [tb]
go
create table [tb]([id] int,[username] varchar(5),[舒张压] int,[收缩压] int,[测量日期] datetime,[录入日期] datetime)
insert [tb]
select 1,'zhang',120,90,'2009-1-1','2009-1-1 11:22:33' union all
select 2,'li',120,85,'2009-1-2','2009-1-2 12:22:22' union all
select 3,'ming',130,89,'2009-1-3','2009-1-3 23:22:33' union all
select 4,'zhang',129,100,'2009-2-3','2009-2-3 22:22:22' union all
select 5,'zhang',120,100,'2009-2-4','2009-2-4 12:20:38' union all
select 6,'li',110,82,'2009-2-4','2009-2-4 22:12:22' union all
select 7,'ming',140,100,'2009-2-4','2009-2-4 11:10:22'
---查询---
select * from tb t
where not exists(select * from tb where username=t.username and 测量日期>t.测量日期)---结果---
id username 舒张压 收缩压 测量日期 录入日期
----------- -------- ----------- ----------- ------------------------------------------------------ ------------------------------------------------------
5 zhang 120 100 2009-02-04 00:00:00.000 2009-02-04 12:20:38.000
6 li 110 82 2009-02-04 00:00:00.000 2009-02-04 22:12:22.000
7 ming 140 100 2009-02-04 00:00:00.000 2009-02-04 11:10:22.000(所影响的行数为 3 行)
insert #tb
select 1,'zhang',120,90,'2009-1-1','2009-1-1 11:22:33' union all
select 2,'li',120,85,'2009-1-2','2009-1-2 12:22:22' union all
select 3,'ming',130,89,'2009-1-3','2009-1-3 23:22:33' union all
select 4,'zhang',129,100,'2009-2-3','2009-2-3 22:22:22' union all
select 5,'zhang',120,100,'2009-2-4','2009-2-4 12:20:38' union all
select 6,'li',110,82,'2009-2-4','2009-2-4 22:12:22' union all
select 7,'ming',140,100,'2009-2-4','2009-2-4 11:10:22'select * from #tb t where not exists (select * from #tb where [username]=t.[username] and [录入日期]<t.[录入日期])
select * from tb a where not exists(select 1 from tb where username=a.username and 录入日期>a.录入日期)
select T.* from T join
(select max(LURURIQI)as luru,username from T group by username) b
on T.lururiqi=b.luru and T.username=b.username
select * from tb where 录入日期 in (select max(录入日期) from tb group by username)
为什么不根据ID来查询呢 万一时间是错的怎么办???