常用SQL收藏

原文:常用SQL收藏

MSSQL Split表字段

--拆分字符串之后匹配结果集合
CREATE FUNCTION [dbo].[fnSplit](
    @sInputList VARCHAR(8000) -- List of delimited items
  , @sDelimiter VARCHAR(8000) = ',' -- delimiter that separates items
) RETURNS @List TABLE (item VARCHAR(8000))

BEGIN
DECLARE @sItem VARCHAR(8000)
WHILE CHARINDEX(@sDelimiter,@sInputList,0) <> 0
 BEGIN
 SELECT
  @sItem=RTRIM(LTRIM(SUBSTRING(@sInputList,1,CHARINDEX(@sDelimiter,@sInputList,0)-1))),
  @sInputList=RTRIM(LTRIM(SUBSTRING(@sInputList,CHARINDEX(@sDelimiter,@sInputList,0)+LEN(@sDelimiter),LEN(@sInputList))))

 IF LEN(@sItem) > 0
  INSERT INTO @List SELECT @sItem
 END

IF LEN(@sInputList) > 0
 INSERT INTO @List SELECT @sInputList -- Put the last item in
RETURN
END

----------------------使用方法
if   object_id('tempdb..#Tmp') is not null
        drop table #Tmp
create table #Tmp --创建临时表#Tmp
(
    ID   VARCHAR(100)
);

DECLARE @iid VARCHAR(100)
declare @name varchar(500)
declare cursor1 cursor for         --定义游标cursor1
select iid,props from Iteminfos               --使用游标的对象
open cursor1                       --打开游标

fetch next from cursor1 into @iid,@name  --将游标向下移1行，获取的数据放入之前定义的变量@iid,@name中

while @@fetch_status=0           --判断是否成功获取数据
begin
IF((select COUNT(*) FROM fnSplit(@name, ';') WHERE  item = '20000:20090')>0)
INSERT INTO #Tmp (ID) VALUES (@iid)
fetch next from cursor1 into @iid,@name  --将游标向下移1行
end

close cursor1                   --关闭游标
deallocate cursor1

SELECT * FROM dbo.Iteminfos WHERE iid IN( SELECT ID FROM #Tmp)

查询节点的函数

create table tb(id varchar(3) , pid varchar(3) , name varchar(10))
insert into tb values('001' , null , '广东省')
insert into tb values('002' , '001' , '广州市')
insert into tb values('003' , '001' , '深圳市')
insert into tb values('004' , '002' , '天河区')
insert into tb values('005' , '003' , '罗湖区')
insert into tb values('006' , '003' , '福田区')
insert into tb values('007' , '003' , '宝安区')
insert into tb values('008' , '007' , '西乡镇')
insert into tb values('009' , '007' , '龙华镇')
insert into tb values('010' , '007' , '松岗镇')
go
-------------创建方法
create function f_cid(@ID varchar(3)) returns @t_level table(id varchar(3) , level int)
as
begin
declare @level int
set @level = 1
insert into @t_level select @id , @level
while @@ROWCOUNT > 0
begin
set @level = @level + 1
insert into @t_level select a.id , @level
from tb a , @t_Level b
where a.pid = b.id and b.level = @level - 1
end
return
END
GO
--------------使用方法
select a.* from tb a , f_cid('001') b where a.id = b.id order by a.id
--------------调用函数查询(广州市)及其所有子节点
select a.* from tb a , f_cid('002') b where a.id = b.id order by a.id

Exists,Datediff,Newid,

---两张关联表，删除主表中已经在副表中没有的信息
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 )

---日程安排提前五分钟提醒
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5

---随机取出10条数据
select top 10 * from tablename order by newid()

-- 类似有 month day year
select * from table1   where convert(varchar,date,120) like   '2006-04-01%'
--datediff
select * from table1   where datediff(day,time,'2006-4-1')=0

删除重复值

--1、查找表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断
select   *   from   people
where   peopleId   in   (select     peopleId     from     people     group     by     peopleId     having     count(peopleId)   >   1)   

--2、删除表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断，只留有rowid最小的记录
delete   from   people
where   peopleId     in   (select     peopleId     from   people     group     by     peopleId       having     count(peopleId)   >   1)
and   rowid   not   in   (select   min(rowid)   from     people     group   by   peopleId     having   count(peopleId   )>1)   

--3、查找表中多余的重复记录（多个字段）
select   *   from   vitae   a
where   (a.peopleId,a.seq)   in     (select   peopleId,seq   from   vitae   group   by   peopleId,seq     having   count(*)   >   1)   

--4、删除表中多余的重复记录（多个字段），只留有rowid最小的记录
delete   from   vitae   a
where   (a.peopleId,a.seq)   in     (select   peopleId,seq   from   vitae   group   by   peopleId,seq   having   count(*)   >   1)
and   rowid   not   in   (select   min(rowid)   from   vitae   group   by   peopleId,seq   having   count(*)>1)   

--5、查找表中多余的重复记录（多个字段），不包含rowid最小的记录
select   *   from   vitae   a
where   (a.peopleId,a.seq)   in     (select   peopleId,seq   from   vitae   group   by   peopleId,seq   having   count(*)   >   1)
and   rowid   not   in   (select   min(rowid)   from   vitae   group   by   peopleId,seq   having   count(*)>1) 

--经典尝试   删除重复值

declare @table table (id int,name nvarchar(10))
insert into @table select 1,'aa'
        union all  select 1,'aa'
        union all  select 2,'bb'
        union all  select 3,'bb'
        union all  select 4,'cc'
        union all  select 1,'aa'
        union all  select 4,'cc'

delete a
from (
    select id,name,rn = row_number() over (partition by id,name order by id) from  @table
) a where rn > 1

select * from @table 

id          name
----------- ----------
1           aa
2           bb
3           bb
4           cc

(4 row(s) affected)

常用日期转换参数

select CONVERT(varchar, getdate(), 120 )
--结果
2004-09-12 11:06:08
select replace(replace(replace(CONVERT(varchar, getdate(), 120 ),'-',''),' ',''),':','')
--结果
20040912110608
select CONVERT(varchar(12) , getdate(), 111 )
--结果
2004/09/12
select CONVERT(varchar(12) , getdate(), 112 )
--结果
20040912
select CONVERT(varchar(12) , getdate(), 102 )
--结果
2004.09.12

行转列

create table tb(姓名varchar(10) , 课程varchar(10) , 分数int)
insert into tb values('张三' , '语文' , 74)
insert into tb values('张三' , '数学' , 83)
insert into tb values('张三' , '物理' , 93)
insert into tb values('李四' , '语文' , 74)
insert into tb values('李四' , '数学' , 84)
insert into tb values('李四' , '物理' , 94)
go

select 姓名 as 姓名,
max(case 课程 when '语文' then 分数 else 0 end) 语文,
max(case 课程 when '数学' then 分数 else 0 end) 数学,
max(case 课程 when '物理' then 分数 else 0 end) 物理,
cast(avg(分数*1.0) as decimal(18,2)) 平均分,
sum(分数) 总分
from tb
group by 姓名

--SQL SERVER 2000 动态SQL。
declare @sql varchar(8000)
set @sql = 'select 姓名 '
select @sql = @sql + ' , max(case 课程 when ''' + 课程 + ''' then 分数 else 0 end) [' + 课程 + ']'
from (select distinct 课程 from tb) as a
set @sql = @sql + ' , cast(avg(分数*1.0) as decimal(18,2)) 平均分, sum(分数) 总分 from tb group by 姓名'
exec(@sql)

--姓名	数学	物理	语文	平均分	总分
--李四	84	94	74	84.00	252
--张三	83	93	74	83.33	250

通过子节点ID得到所有父节点

ALTER function [dbo].[f_cid](@id int)
returns @t table(id int,[name] varchar(30),parentid int,lev int)
as
begin
     declare @lev int
     set @lev=1
     insert into @t SELECT cid,name,parent_cid,@lev from  TB_ItemCats where cid=@id
     while(@@rowcount>0)
     begin
          set @lev=@lev+1
          insert into @t select a.cid,a.name,a.parent_cid,@lev from TB_ItemCats a,@t b
          where a.cid=b.parentid and b.lev=@lev-1 AND a.cid NOT IN (select b.id from @t)
     end
     return
END

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