sql

合并不同行数的两个表格的数（A表里的一个值a，与另B表的行数同步，即新表行数与B一样，由a+B表查出的各行组成）：

以下三种效果一样，第三种效果最佳：

1.select sV,PD,Sh,Pro
from
(Select sV From Sy where sN='Cur' ) t1,
(Select PD,Sh,Pro From P ) t2

2.select * from (Select  sV From Sywhere sN = 'Cur' )  left join    (Select PD, Sh, Pro From   P) on 1 = 1

3.select sV,PD,Sh,Pro From Sy    left join P on 1=1  where sN = 'Cur'

4.利用存储过程据一条记录插入不同记录的数据

create procedure upAddRecord
as
declare @t int
set @t=1

while (@t<=100)
begin
insert into [DATABaseName].[dbo].[table_name] ([column1], [column2],[column3],[column4],[column5],[column6],[column7],[column8],[column9],[column10]) 
VALUES ('testB'+convert(varchar(20),@t), 'testB'+convert(varchar(20),@t),GETDATE()-@t,'01','wu','test','test2','test3',1,GETDATE()) 
set @t=@t+1
end
go
DROP PROCEDURE upAddRecord
select * from table_name where [column6]='test' order by [column3] desc

 5.查看是否存在相同数据的列的sql

Select 列名,COUNT(列名)
 FROM  表名
 GROUP BY 列名
 HAVING COUNT(列名) >1

 6.在做Sql Server开发的时候有时需要获取表中今天、昨天、本周、上周、本月、上月等数据，这时候就需要使用DATEDIFF()函数及GetDate()函数了。

DATEDIFF ( datepart , startdate , enddate )
释义：计算时间差
datepare值：year | quarter | month | week | day | hour | minute | second | millisecond
startdate：开始日期
enddate ：结束日期
GetDate()
释义：获取当前的系统日期

下面例子中表名为tablename,条件字段名为inputdate
查询今天

SELECT * FROM tablename where DATEDIFF(day,inputdate,GETDATE())=0
查询昨天

SELECT * FROM tablename where DATEDIFF(day,inputdate,GETDATE())=1
查询本周

SELECT * FROM tablename where  datediff(week,inputdate,getdate())=0
查询上周

SELECT * FROM tablename where  datediff(week,inputdate,getdate())=1
查询本月

SELECT * FROM tablename where DATEDIFF(month,inputdate,GETDATE())=0
查询上月

SELECT * FROM tablename where DATEDIFF(month,inputdate,GETDATE())=1

 按小时分段统计

DECLARE @startTime datetime = '2017-09-01 12:13:00'
DECLARE @split INT=300 --分段统计（秒）
SELECT COUNT(*) AS 数量,DATEADD(s,DATEDIFF(s, '1970-01-01 00:00:00', [Time])/@split*@split, '1970-01-01 00:00:00') AS Time 
FROM DateUpload 
WHERE Time >= @startTime 
GROUP BY DATEDIFF(s, '1970-01-01 00:00:00', [TGSJ])/@split
ORDER BY 数量 desc;

选择后面30秒的数据

1 SELECT TOP (10) *  FROM DateUpload 
　　　　　　WHERE (IsUpLoad = 0 and id is not null and Time<DATEADD(SS,-30,GETDATE()) and Type in (0,1)) ORDER BY Time DESC

参考：http://www.cnblogs.com/mayi1/p/5946536.html