create database MyDatabseOne;	--建立資料庫
drop database MydatabaseOne;	--刪除資料庫;

--如果直接點"執行"將是執行所有語句,而選中某些則是單獨執行
--以下程式碼建立資料庫的初始值
create database MydatabaseOne		--建立資料庫
on primary
(
	--配置主資料檔案
	name='MydatabaseOne',		--主資料檔案的邏輯名稱
	filename='C:\Users\Rao\Desktop\MydatabaseOne.mdf',		--主資料的實際儲存路徑
	size=3mb,			--主資料的初始大小
	maxsize=100mb,		--主資料庫的最大大小
	filegrowth=20%		--主資料庫每次增長的大小(最後一個可以不用逗號)
)
log on
(
	name='MydatabaseOne_log',	
	filename='C:\Users\Rao\Desktop\MydatabseOne_log.ldf',
	size=1mb,
	filegrowth=1mb
)


--建一表,為員工表
use School
create table Employess
(
	EmpID int identity(1,1) not null,
	EmpName nvarchar(50) not null,
	EmpGender nchar(1) not null,
	EmpAge int,
	EmpJoinDate date,
	EmpPhone nvarchar(11) not null
)
--另一表,部門,將引
create table Department
(
	DepID int identity(1,1) not null,
	DepName nvarchar(50) not null
)
--閱表
select * from Department
select * from Employess

--增之為Dep
insert into Department values('中國市場研發部')
--增之為Emp
insert into Employess values('Heil','女',28,'2016-12-31','12345678901')
--刪其一列
--自動編號
set identity_insert Department on
insert into Department(DepID,DepName) values(3,'erro')
set identity_insert Department off

--修改
update Employess set empage=28,EmpJoinDate='2017-01-01',EmpPhone='159357852' where EmpName='Heil'
--以條件刪,無則全刪,如需高效,truncate table Department
delete from Department where DepName='erro'

--刪列
alter table Employess drop column EmpJoinDate
--增列
alter table Employess add  EmpJoinDate nvarchar(50)
--修改資料型別
alter table Employess alter column EmpPhone nvarchar(20)
--增列主鍵約束
alter table Employess add constraint PK_Employess_EmpID primary key(EmpID)
--增非空約束
alter table Employess alter column EmpAge nvarchar(20) not null
--增唯一約束
alter table Employess add constraint UQ_Employess_EmpName unique(EmpName)

select * from Employess
delete from Employess where EmpName='Heil'

--增加預設約束
alter table Employess add constraint DF_Employess_EmpGender default('男') for EmpGender
--增加檢查約束
alter table Employess add constraint CK_Employess_EmpGender check(EmpGender='男' or EmpGender='女') 
alter table Employess add constraint CK_Employess_EmpAge check(EmpAge>18 or EmpAge<=35)
select * from Employess
update Employess set empIDCard='123456789111111'
alter table Employess add EmpIDCard nvarchar(18) 
alter table Employess alter column EmpIDCard nvarchar(18) not null
alter table Employess add constraint CK_Employess_EmpIDCard check(len(EmpIDCard)=15 or len(EmpIDCard)=18)

--主鍵約束
alter table Department add constraint PK_Department_DepID primary key(DepID)
--外來鍵約束
alter table Employess add DepID int 
update Employess set DepID=1
alter table Employess alter column DepID int not null
alter table Employess add constraint FK_Employess_Department foreign key(EmpID) references Department(DepID)

--棄約
alter table Employess drop constraint 
CK_Employess_EmpIDCard,
FK_Employess_Department
--多增約束
alter table Employess add 
constraint FK_Employess_Department foreign key(EmpID) references Department(DepID),
constraint CK_Employess_EmpIDCard check(len(EmpIDCard)=15 or len(EmpIDCard)=18)
---------------查詢

---查詢整表
--*號為所有行所有列均查詢
select * from TblStudent 
--查詢某些列
select tsid,tsname,tsgender from TblStudent
--條件查詢行
select tsid,tsname,tsgender from TblStudent where tSClassId=2
--為查詢結果的列起別名(as一般情況可省略,但如果列名中有非法字元,可用引號將別名引起來'(學生編號)',
--或者可以  學生編號=tsid   
--也可隨意增加一個別名列如  婚否='否')
select 
	tsid as 學生編號,
	tsgender as 性別,
	tsphone as 聯絡電話 
from TblStudent

select 當前時間=GETDATE()

--去除查詢結果中的重複項(distinct只能去除查詢結果之後的重複)
select distinct tsname,tsgender from TblStudent

---------排序
--按照年齡,降序(desc)升序為(asc ,空會在最前,預設不寫為升序)
select *from TblStudent order by tSage desc
--查詢年齡最小的前3個
select top 3 * from TblStudent order by tsage
--表示式需要()
select top (1+3) * from TblStudent order by tsage
--取前百分比(如不為整數,則向上取整,例如3.0取3,而3.1%取4)
select top 3 percent *from TblStudent order by tsage

-----聚合函式,不統計空值
--查詢最大值
select max(tsage) from TblStudent
--查詢最小值
select min(tsage) from TblStudent
--查詢總和
use School
select sum(tsage) from TblStudent
--統計多少條資料(*可以為任意值,空不統)
select count(*) from TblStudent where tSClassId=1
--平均值
select avg(tsage*1.0) from TblStudent

select 年齡最大=max(tsage),年齡最小=min(tsage),平均年齡=avg(tsage),總條數=count(tsage) from TblStudent

select * from TblStudent
--between  and  等價於 and
select tsname from TblStudent where tSage between 13 and 17
select tsname from TblStudent where tsage>=13 and tsage<=17

--in 等價多or 但如果查詢的是如(3,4,5)此類連續資料,可以直接tsclassid>3 and tsclassid<5,此法更高效
select * from TblStudent where tSClassId in (1,3,30)
---模糊查詢- _ % ^ []  ([-]篩選範圍)
--   _   表示任意單個字元
select * from TblStudent where tSName like '張_'
-- % 任意多個任意字元
select * from TblStudent where tSName like '張%'
--查詢所有帶%(注:%是一個萬用字元,所以需要用[]轉義)的資料
select * from TblStudent where tSName like '%[%]%'

--自定義轉義符(例中指定\後為轉義字元,其後的緊跟字元為普通字元,不再是系統預設
select * from TblStudent where tSName like '%\[%' escape '\'
use School
select * from TblStudent
select * from TblStudent where tSAddress=null
--查詢空值,以is null / not null 僅針對數值型別,字串型別如為空則不為null
select * from TblStudent where tSAddress='null'
--任何值和null計算後所得結果亦為null
select 2000+null
---通過order by排序,一定要在整個SQL語句的最後(在where之前)
--降序用desc ,升序用asc(亦可為空)
select tsage from TblStudent order by tsage desc
select * from TblStudent
--雙降序
select * from TblStudent order by tsage desc,tSClassId
--統計每個ID下的人數
select 班級ID=tsclassid,班級人數=count(*) from TblStudent group by tSClassId
select 性別=tsgender,人數=count(*) from tblstudent group by tsgender
--統計班級中id下男同學的個數
--使用group by(當使用了此分組語句時,不能再包含其它列的查詢,除非此列也出現在聚合函式中)
select 班級ID=tsclassid,男同學人數=count(*) from TblStudent where tSGender='男' group by tSClassId
use School
select 班級ID=tsclassid,男同學人數=count(*),男同學平均年齡=AVG(tsage) from TblStudent where tSGender='男' group by tSClassId

----having與where的區別,where以什麼進行分組,而having是分組之後進行篩選
---只保留班級人數大於1的
select 
	班級ID=tsclassid, 
	班級人數=count(*)
	from TblStudent
	group by tSClassId
	having count(*)>1

select '100+1100'

-------------型別轉換函式------------
--cast  cast(原資料 as 新型別)
select 100.0+cast('1000' as int)
--convert(資料型別,原資料)
select 100.0+convert(int,'1000')
select '您的班級編號:'+convert(char(1),1)

-----聯合union----
--聯合的資料列的型別必須一致
--union all 不會對聯合的資料去除重複,並且不會排列
--union 會去除重複,並且排列
--大多數的時候不需要去除重複,也並不需要重新排列,所以一般建議使用union all
select tsname,tSId from TblStudent
--union all
select ttname,tTId from TblTeacher
----使用union all插入資料
select * from TblTeacher

insert into TblTeacher
select '李四',0,30,4000,'1986-1-1'
union all
select '王五',0,30,4000,'1986-1-1'
select '李四',0,30,4000,'1986-1-1'
union all
select '王五',0,30,4000,'1986-1-1'


------備份表------
use School
----從TblStudent表查詢所有列並插入到一張新表中
----約束不會複製
select * into TblStudent2017 from TblStudent
select * from TblStudent2017
drop table TblStudent2017
----只複製表結構
select top 0 * into TblStudent2017 from TblStudent

----向表中追加資料
insert into TblStudent2017 values('date','男','湖北','13855968545',26,'1991-12-15',1,1)
select * from TblStudent
---追加資料
insert into TblStudent2017
select tsname,tsgender,tsaddress,tsphone,tsage,tsbirthday,tSCardId,tsclassid 
from TblStudent 
where tSGender='女'


-------------------常用字串函式-------------.
------1.計算字元的個數
print len('HI,how are you')
------2.返回所佔用的位元組的個數,非字串
print datalength('HI')
------3.upper(),lower(),大小寫
print upper('hi')
print lower('HI')
------4.去掉兩端空格ltrim()去掉左端,rtrim()去掉右端空格
print '==========='+rtrim(ltrim('         Hello         '))+'==============='
------5.字串擷取函式
print left('hihihi',2)
print right('hihiii',2)
print substring('abcdefg',1,1)   --下標從1開始,如果下標小於1,則往前會推一個空值


-----------日期函式--------
print getdate()
print sysdatetime()
----dateadd()增加時間
---增加天數,100天,從當前時間 month 月 year 年 minute分鐘 second秒 hour小時
print dateadd(day,100,getdate())

-----查詢大於30歲的人
select * from TblStudent
select * from TblStudent where dateadd(year,30,tSBirthday)<=GETDATE()

--datediff()計算 兩個日期 的差
print datediff(year,'1990-12-15',getdate())
print today()

---計算學生年齡
select * from TblStudent
select *, 年齡=DATEDIFF(year,tsbirthday,getdate())  from TblStudent
select 年齡=DATEDIFF(year,tsbirthday,getdate()),人數=count(*)  from TblStudent
group by DATEDIFF(year,tsbirthday,getdate()) 

----獲取日期部分
print datepart(year,getdate())
print datepart(dayofyear,getdate())   --獲取自開始至目前的天數

---datename()
print datename(year,getdate())		--同樣打印出當前年,但不同於以上,此為列印的字串形式,無法進行與其它數值型別計算

----*不在要表中,無法執行--
----計算本月呼叫員撥打電話的時間,取前三名
select * from CallRecords
top 3			--取前三名
呼叫員編號=CallNumber,
呼叫員時長=datediff(second,starttime,endtime)
where datediff(month,satarttime,endtime)=0			--表示本月
group by CallNumber		--按照呼叫員來分組
order by 呼叫員時長 desc			--以呼叫員時長排序,降序

select * from TblStudent
delete  from TblStudent where tsname='vs2015'

update TblStudent set tSName='吳廣' where tSName='weweew'
 select tsname from tblstudent

 select * from person
 insert into person values('測試','男',18)
 select count(*) from person

 select * from usertable

select count(*)  from usertable where username='admin' and userpwd='admn'

insert into person 
select 'add','男',21
union all
select 'add','男',21
union all
select 'add','男',21
union all
select 'add','男',21

use school
select * from person
-----獲得剛剛插入語句的自動編號
insert into person output inserted.PId values('ggg','男',30)
select * from UserTable

select * from usertable where username='aa' or 1=1;insert into UserTable values('ggg','ggg') --'
select * from usertable where username='aa' or 1=1;insert into UserTable values('ggg','ggg','ggg') --'

select count(*) from usertable where username='admin' and userpwd='admin'

insert into Person(PName,PGender,PAge) values('dsfkjds','男',30)
update Person set PName='111' where PId=2
select count(*) from UserTable

select * from NoteBookList where NParentID=-1

select dConet from book where dName='C#從入門到精通'


select * from book
insert into book values(14,'盛世婚寵','2017-03-25','2616','2017-03-25',0)

use School

select * from UserTable

select * from Phonegroup
select * from PhoneNumber

--內連線查詢
select pname,pgender,phone,pgroup from  PhoneNumber join Phonegroup on phoneGroup.pid=phonenumber.parentid

select * from Person

use school

select PhoneNumber.pid,pname,pgender,page,phone,pgroup,PhoneGroup.PId from  PhoneNumber join Phonegroup on phoneGroup.pid=phonenumber.parentid

---case的用法----
----相當於C#中的if else  此項可以區間判斷
--then後面的資料型別全部必須一致
select * ,
	級別=case
				when Level=1 then '菜鳥'
				when level=2 then '老鳥'
				when level=3 then '烤雞'
				else '骨灰'
			end
from BBSLevel
--相當於C#中的switch  此項只能等值判斷
select * ,
	級別=case level
				when 1 then '菜鳥'
				when 2 then '老鳥'
				when 3 then '烤雞'
				else '骨灰'
			end
from BBSLevel

--練習
select 
	ttname,
	ttage,
	tTSalary,
	工資級別=case ttsalary/1000
						when 1 then '水貨'
						when 2 then '一般'
						when 3 then '還行'
						when 4 then '不錯'
						else '牛人'
					end
from TblTeacher

create table TestA
(
	A int,
	B int,
	C int
)
insert into testA values(10,20,30)
insert into testA values(20,30,10)
insert into testA values(30,10,20)
insert into testA values(10,20,30)

select * from TestA
--A列大於B列顯示A列值,B列大於C列顯示C列的值
select 
	X=case	
			when A>B then A
			else B
		end,
	Y=case 
			when B>C then C
			else C
		end
from TestA

create table test
(
	number varchar(10),
	amount int
)
insert into test(number,amount) values('RK1',10)
insert into test(number,amount) values('RK1',20)
insert into test(number,amount) values('RK1',-30)
insert into test(number,amount) values('RK1',-10)

select 
	單號=number,
	收入=case
				when amount>0	then amount else 0
			end,
	支出=case 
				when amount<0 then abs(amount) else 0
			end
from test

select * from teamscore

select 
	隊名=teamName,
	勝=sum(case
			when gameresult='勝' then 1 else 0
		end),
	負=sum(case 
			when gameresult='負' then 1 else 0
		end)
from teamscore
group by teamname

select * from nbascore

select 
	隊伍名稱=teamName,
	第1賽季得分=sum(case 
						when seasonname='第1賽季' then score
						end),
	第2賽季得分=sum(case 
						when seasonname='第2賽季' then score
						end),
	第3賽季得分=sum(case 
						when seasonname='第3賽季' then score 
						end)
from nbascore
group by teamName

---分頁查詢--
--row_number() over ()
select * from TblStudent2017
---確定以年齡升序排序進行編號
select *,rn=ROW_NUMBER() over (order by tsage asc) from TblStudent2017
--將編好號的查詢語句當子查詢語句進行查詢
--每頁3條,查詢第3頁為 (3-1)*3+1 至 3*3
select *
from (select *,rn=ROW_NUMBER() over (order by tsage asc) from TblStudent2017)
as t where t.rn between (3-1)*1+1 and 3*3

select count(*) from TblStudent2017
.
SELECT * FROM Person

------------------------TSQL程式設計-----------
--1.宣告變數
declare @name nvarchar(50)
declare @age int
declare @gender nchar(1),@id int
--2.為變數賦值
set  @name='xxoo'
select @age=18
select @gender='男',@id=1
--3.輸出
select 姓名= @name
select 年齡= @age
select 性別
 
[email protected],@id

----while迴圈
declare @i int=1
while @i<=100
begin
	print @i
	set @[email protected]+1
end

--計算1-100的和
declare @i int=1
declare @sum int=0
while @i<=100
begin
	set @[email protected][email protected]
	set @[email protected]+1
end
print @sum

--計算1-100之間所有整奇數與偶數的和
declare @j int=1
declare @jsum int=0
declare @osum int=0
while @j<=100
begin
	if @j%2 =0
	begin
		set @
 
[email protected][email protected]
	end
	if @j%2<>0
	begin
		set @[email protected][email protected]
	end
	set @[email protected]+1
end
print @osum
print @jsum

--一般情況下兩個@@是系統變數,但如果是手動宣告的,則為全域性變數
print @@LANGUAGE    

---------事務
--轉賬示例
select * from bank
begin transaction
	declare @sum int =0		--宣告變數用來儲存如果出錯的條數
	update bank set money=money+10 where id='001'
	set  @
 
[email protected][email protected]@error		--確定是否有出錯,有則加上
	update bank set money=money-10 where id='002'
	set @[email protected][email protected]@error
	if @sum<>0		--如果不等於0,則有出錯
	begin
		rollback		--讓所有操作回滾
	end
	else
	begin
		commit		--提交所有操作
	end

---------------儲存過程
------------相當於方法
--------1.無參無返回值的
create proc usp_select_tblteacher_salary
as
begin
	select * from TblTeacher where tTSalary>2000
end
--呼叫儲存過程
exec usp_select_tblteacher_salary

-----2.帶引數的儲存過程
create proc usp_add
@num1 int,
@num2 int
as
begin
	select @[email protected]
end
--呼叫
exec usp_add 100,1

---帶返回值的(輸出引數)
alter proc usp_count
@count int output
as
begin
	set @count=(select count(*) from TblStudent)
end
--呼叫
declare @cont int
exec usp_count @[email protected] output
print @cont

---構建分頁查詢的儲存過程
alter proc usp_bank
@pagesize int=7,		--每頁顯示條數
@pageindex int=1,		--當前檢視第幾頁的記錄
@pagecount int output,		--總條數
@tablecount int output --總頁數
as
begin
	select *
	from (select *,rn=ROW_NUMBER() over(order by Money asc) from bank) as t
	where t.rn between (@pageindex-1)*@pagesize+1 and @pageindex*@pagesize
	--計算記錄的總條數
	set @pagecount=(select count(*) from bank)
	--計算總頁數,向上取整
	set @tablecount=CEILING(@pagecount*1.0/@pagesize)
end

-----C#dal呼叫
 public List<NewListMl> PageFromProc(int pageIndex,int pageSize,string typeID,out int total)
        {
            SqlParameter pi = new SqlParameter("@pageIndex", pageIndex);
            SqlParameter ps = new SqlParameter("@pageSize", pageSize);
            SqlParameter ti = new SqlParameter("@tyID", typeID);
            SqlParameter to = new SqlParameter("@total", System.Data.SqlDbType.Int);
            to.Direction = System.Data.ParameterDirection.Output;
            
            SqlParameter[] pms =
            {
               pi,ps,ti,to
            };
           //呼叫方法得到資料
           List<NewListMl> list= GetListModel("LoadPage", System.Data.CommandType.StoredProcedure, pms);
		   //得到儲存過程輸出的總條數
            total = (int)to.Value;
            return list;
        }

declare @pc int
declare @pt int
exec usp_bank @pagesize=6,@pageindex=5,@[email protected] output,@[email protected] output
print @pc
print @pt

--------------------------------------------set與select的區別
declare @a int
--set @a=(select count(*) from bank)
select @a=count(*) from bank
print @a

----當查詢語句得到多個值的時候,則set會報錯,而select會得到最後一個查到的值
declare @a int
--set @a=(select money from bank)
select @a=money from bank
print @a

--------------------------------------------轉賬示例(儲存過程+事務)
alter proc usp_zz
 @decimal int ,--轉出/收到錢數
 @zid1 nvarchar(4), --轉賬編號
 @zid2 nvarchar(4), --/收賬人編號 
 @reslut	int output	--判斷是否轉賬成功,1,表示成功,2.表示失敗,3.表示餘額不足,4,表示不存在轉賬的id
as
begin
	-------判斷是否存在編號
	declare @count1 int		--宣告一個變數,用來儲存是否有收賬人編號
	select @count1=count(*) from bank where [email protected]		--如果有,則返回1,沒有則為0
	declare @count2 int		----宣告一個變數,用來儲存是否有收賬人編號
	select @count2=count(*) from bank where [email protected]		--如果有,則返回1,沒有則為0
	if @count1<>1 or @count2<>1		--判斷其值是否1,有一個不為1,則為false,此處為為false
	begin
		set @reslut=4			--為false,則有一個編號是沒有,即返回4
	end
	else			--如果有,則繼續以下程式碼
	begin	
		--1.判斷金額是否足夠
		declare @money int 
		select @money=money from bank where [email protected]
		if @[email protected]>=10
		begin
			--開始轉賬
			begin transaction 
			declare @sum int =0
			--1.加錢
			update bank set [email protected] where [email protected]
			set @[email protected][email protected]@ERROR
			--2.扣錢
			update bank set [email protected] where [email protected]
			set @[email protected][email protected]@ERROR
			--3.判斷是否成功
			if @sum<>0
			begin
				set @reslut=2		--轉賬失敗
				rollback
			end
			else
			begin
				set @reslut=1		--轉賬成功
				commit
			end
		end
        else
        begin
            set @reslut=3		--餘額不足
        end	
	end	
end


--------------------------------------------------------------------------
declare @isok int
exec usp_zz @decimal= 20,@zid1= '004',@zid2='001',@[email protected] output
print @isok
select * from bank

select count(*) from bank where id='001'

declare @count1 int
select @count1=count(*) from bank where id='001'
print @count1

declare @count2 int
select @count2=count(*) from bank where id='002'
print @count2
declare @isok int
if @count1<>1 or @count2<>1
begin
	set @isok=0
end
else
begin
	set @isok=1
end
print @isok
----------------------------------------------------------------------
--------------增刪改查的儲存過程封裝-----------------------------
-----以Table表為例
--select * from [Table]
----增加
create proc usp_insert_table
	@name nvarchar(50),
	@desc nvarchar(500)
as
begin
	insert into [Table] values(@name,@desc)
end
------
exec usp_insert_table '高二一班','這是我第一個新建的'

-----刪除(根據班級編號)
create proc usp_delete_table
	@id int
as
begin
	delete  from [table] where 班級編號[email protected]
end
-----
exec usp_delete_table 1

----修改(根據班級編號)
create proc usp_update_table
	@name nvarchar(50),
	@desc nvarchar(500),
	@id int
as
begin
	update [table] set 班級名稱[email protected],班級描述[email protected] where 班級編號[email protected]
end
----
exec usp_update_table '高二二班','這是我修改過的',1

---查詢
create proc usp_select_table
as
begin
	select * from [table]
end


-- 讓欄位區分大小寫查詢
設計表,選中相應的欄位,排序規則中,選擇區分大小寫

--去除重複
DELETE t FROM (SELECT *,ROW_NUMBER()OVER(PARTITION BY title ORDER BY RAND()) AS RN FROM BookInfo) AS t WHERE RN>1

給每行某欄位新增100內的隨機數
UPDATE BookInfo SET BookInfo.count = CEILING(rand(checksum(newid()))*100)


--獲取所有表名
select table_name,table_type from INFORMATION_SCHEMA.TABLES 

--獲取指定表的欄位名和欄位資料格式
--獲取指定表的欄位名和欄位資料格式
select column_name,DATA_TYPE,CHARACTER_MAXIMUM_LENGTH,IS_NULLABLE from INFORMATION_SCHEMA.COLUMNS t where t.TABLE_NAME='Users'

--獲取所有資料庫名稱
select name from master..sysdatabases where name not in('master','model','msdb','tempdb')

--獲取指定資料庫中的所有表
use BookStore
select table_name from INFORMATION_SCHEMA.TABLES 

--查詢空("或NULL")資料
select * from tb_table where filed is null or filed = ''

--查詢銷售量佔前50%的圖書資訊
select top 50 percent 書名,書號,sum(銷售數量) as 合計銷售數量 from tb_Book group by 書號,書名,作者 order by 3 desc

--判斷是否為數值
select 姓名,isnumeric(年齡) from tb_Student

--在查詢時對數值進行取整
select dm as 數值取整前,ceiling(dm) as 數值取整後 from tb_money
注:還有  Floor函式 Round(dm,2)四捨五入,2為保留的小數位數 ABS(求絕對值)

--在查詢中生成隨機數
select floor(rand()*50)
示例:select * from tb_Student where 學生編號=22050110+floor(rand()*10)  --隨機生成大於0小於1的小數數值後與10相乘,並對小數數值向下取整

--實現字串的大小寫轉換
select friendname as 字串 lower(friendname) as 全部轉小寫,upper(friendname) as 全部轉大寫 from tb_string

--返回字元在字串中出現的次數
select friendname as 字串 (len(friendname)-len(replace(friendname,'i','')))/len('i') as 出現指定字元的次數 from tb_string

--其它各類函式
substring(str,index,lenght) 	--同C#
stuff(str,index,lenght,'del')  --刪除指定長度的字元


select ABS(-12),	--求絕對值
CEILING(12.3),	--向上取整
FLOOR(12.3),	--向下取整
ROUND(12.333,1),	--四捨五入,第二個引數為保留的位數
RAND()*10,	--隨機數,生成0-1隨機浮點數
SIGN('11.3'),	--判斷指定資料列中的數值是否為正數(返回1),負數(返回-1),0(返回0) SIGN(1)
LOWER('HELLO'),	--小寫
UPPER('hello'),  --大寫
SUBSTRING('電腦科學與技術',2,3),	--擷取指定字串從第2位開始共擷取3個字元
STUFF('電腦科學與技術',2,3,'11'),	--相當於替換了,此例將算機科替換成了11,如果替換成空,則會刪除
CHARINDEX('學與','電腦科學與技術'),	--查詢字串在另一字串中的初始位置
REPLACE('電腦科學與技術','機科','科機'),	--替換
ISDATE('1992/2/22'),	--判斷是否日期,是則返回1
YEAR('1992/2/22'),MONTH('1992/2/22'),DAY('1992/2/22')	--分別返回年,月日

select DATENAME(weekday,getdate()),	--返回當前的星期
	   DATEDIFF(YEAR,'1992/02/22',getdate())	--計算年齡,中間出生日期的引數只用符合datetime即可,例如19920222