㈠ 如何用sql查询出最新的记录变化详见以下描述,谢谢!
oracle的写法:
SELECT
*
(
SELECT
c.* ,
row_number() over (partition by c.timech order by a.timech desc) rn
FROM
(
SELECT
Xh,
xm,
zt,
timech
FROM
Student
UNION ALL
SELECT
b.Xh,
b.xm,
a.ztchange,
a.timech
FROM
Change a,
Student b
WHERE
a.xh = b.xh
and c.timech <= '2011.1.20'
)
c
)
WHERE
rn = 1
㈡ sql如何查询每个用户最新的一条信息
你的from和to是关键字,这里用id1和id2表示。
创建表及插入数据(在你基础上多加了一条数据):
createtabletest
(id1int,
id2int,
timedatetime)
insertintotestvalues(1,2,'2017-03-1615:18:00')
insertintotestvalues(2,1,'2017-03-1615:21:00')
insertintotestvalues(1,2,'2017-03-1616:00:00')
执行:
selectt2.*from
(selectcasewhenid1>id2thenid1elseid2endid1,
casewhenid1>id2thenid2elseid1endid2,
max(time)>id2thenid1elseid2end,casewhenid1>id2thenid2elseid1end)t1,
testt2
where(t1.id1=t2.id1andt1.id2=t2.id2andt1.time=t2.time)or(t1.id1=t2.id2andt1.id2=t2.id1andt1.time=t2.time)
结果:
㈢ 怎样在sql表查询最新10条记录
select*from
(selecttop10*from表名orderbydate1)table1orderbydate1desc
以上这段sql语句是查询表中最新的10条记录
第一步是要按照“日期”降序排列
第二步取前10条
㈣ 用SQL语句怎样从表里查询出最新的8条信息
select top 8 * from gonggao order by gonggaoid desc
㈤ 首页新闻列表中,按时间显示最新插入数据库的5条新闻信息,SQL查询语句应该怎么写
select top 5 N_ID,N_TITLE,N_TIME from 表的名字 Order by N_TIME desc
㈥ sql查询最近一天更新状况
select *
from table
where trunc(收发短信时间) = trunc(sysdate)
一个月/年 就截取日期 即可
㈦ MYSQL查询一张表如何查询出最新信息
假设表名是D, 正确答案如下:
select t2.eid, t2.ename, t2.yearmonth
from D t2
join
(
select t1.eid, max(t1.yearmonth) as yearmonth
from D t1
group by t1.eid
) t3
on t2.eid = t3.eid and t2.yearmonth = t3.yearmonth
运行通过后请采纳,谢谢!
㈧ sql 查数据库中时间最新的一条记录
select *,max(create_time) from a
where create_time<="2017-03-29 19:30:36"
group by user_id
这句可以理解为将结果集根据user_id分组,每组取time最大一条记录。这样就很好的实现了批量查询最近记录,并且仅仅需要遍历一次表,即使在数据量巨大的情况下也可以在很短的时间查出结果。
(8)sql最近新消息扩展阅读:
SQL数据查询语句
1、语句语法简单归纳为:
SELECTselect_list[INTOnew_table_name] [FROMtable_source]
[WHEREsearch_condition] [GROUP BYgroup_by_expression]
[HAVINGsearch_condition] [ORDER BYorder_expression[ASC | DESC]]
2、WITH子句用于指定临时命名的公用表达式,在单条语句(SELECT、INSERT、UPDATE、DELETE)的语句执行范围内定义。
3、LIKE关键字
用于模糊查询,通配符有%、_、[ ]、[^]
%:后面可以跟零个或多个字符
_:匹配任意单个字符
[ ]:查询一定范围内的单个字符,包括两端数据
[^]:表示不在一定范围内的单个字符,包括两端数据
㈨ sql取各个栏目最新的几条信息
--查每个分组前N条记录
--> 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)
*/
--得到每组前几条数据
--假设每组Col1中, Col3不会重复
--建立测试环境
Create Table TEST
(Col1 Varchar(10),
Col2 Varchar(10),
Col3 Int)
--插入数据
Insert TEST Select 'BD1V','Label', 4
Union All Select 'BD1V', 'BATT', 2
Union All Select 'BD1V', 'ODD', 3
Union All Select 'BD1V', 'HDD', 5
Union All Select 'BD1V', 'LCD', 1
Union All Select 'BD1W','HDD', 3
Union All Select 'BD1W','RAM', 8
Union All Select 'BD1W','TP CABLE', 5
Union All Select 'BD1W','LCD', 6
Union All Select 'BD1W','Label', 2
Union All Select 'BL3', 'LCD CABLE', 7
Union All Select 'BL3', 'LABEL', 6
Union All Select 'BL3', 'LCD', 5
Union All Select 'BL3', 'RAM', 1
Union All Select 'BL3D', 'Label', 4
GO
--测试
--方法一:
Select Col1, Col2, Col3 From TEST A
Where (Select Count(*) From TEST Where Col1 = A.Col1 And Col3 > A.Col3) < 3
Order By Col1, Col3 Desc
--方法二:
Select Col1, Col2, Col3 From TEST A
Where Exists (Select Count(*) From TEST Where Col1 = A.Col1 And Col3 > A.Col3 Having Count(*) < 3)
Order By Col1, Col3 Desc
--方法三:
Select Col1, Col2, Col3 From TEST A
Where Col3 In (Select TOP 3 Col3 From TEST Where Col1 = A.Col1 Order By Col3 Desc)
Order By Col1, Col3 Desc
GO
--删除测试环境
Drop Table TEST
--结果
/*
Col1 Col2 Col3
BD1V HDD 5
BD1V Label 4
BD1V ODD 3
BD1W RAM 8
BD1W LCD 6
BD1W TP CABLE 5
BL3 LCD CABLE 7
BL3 LABEL 6
BL3 LCD 5
BL3D Label 4
*/
㈩ 查询指定用户ID发布的的最新信息SQL怎么写
假设你有一张表存储了最新发布信息,当中存在发布时间列,则你可以这样写:
select * from 发布信息表 p
join
(
select 用户ID,max(发布时间) as '最新发布时间'from 发布信息表
where 用户ID='××'
--如果你是多个用户查询,改成把“=”改成in,然后在 where后面加上group by 用户ID
) s
on p.用户ID=s.用户ID and p.发布时间=s.最新发布时间