sql數(shù)據(jù)庫(kù)命令大全

1、公告： HYPERLINK http:/forum./SList/blogSupport t _blank 意見(jiàn)反饋 HYPERLINK /blogdevteam t _blank 官方博客 sql數(shù)據(jù)庫(kù)命令大全 SQLServer和Oracle的常用函數(shù)對(duì)比1.絕對(duì)值 S:select abs(-1) valueO:select abs(-1) value from dual2.取整(大) S:select ceiling(-1.001) value O:select ceil(-1.001) value from dual3.取整（小） S:select floor(-1.001) val

2、ue O:select floor(-1.001) value from dual4.取整（截取）S:select cast(-1.002 as int) value O:select trunc(-1.002) value from dual 5.四舍五入S:select round(1.23456,4) value 1.23460O:select round(1.23456,4) value from dual 1.23466.e為底的冪 S:select Exp(1) value 2.7182818284590451 O:select Exp(1) value from dual 2.7

3、18281827.取e為底的對(duì)數(shù)S:select log(2.7182818284590451) value 1O:select ln(2.7182818284590451) value from dual; 18.取10為底對(duì)數(shù)S:select log10(10) value 1O:select log(10,10) value from dual; 19.取平方S:select SQUARE(4) value 16O:select power(4,2) value from dual 1610.取平方根S:select SQRT(4) value 2O:select SQRT(4) val

4、ue from dual 211.求任意數(shù)為底的冪S:select power(3,4) value 81O:select power(3,4) value from dual 8112.取隨機(jī)數(shù)S:select rand() value O:select sys.dbms_random.value(0,1) value from dual;13.取符號(hào)S:select sign(-8) value -1O:select sign(-8) value from dual -1數(shù)學(xué)函數(shù)14.圓周率S:Select PI() value 3.1415926535897931O:不知道15.sin,

5、cos,tan 參數(shù)都以弧度為單位例如：select sin(PI()/2) value 得到1（SQLServer）16.Asin,Acos,Atan,Atan2 返回弧度17.弧度角度互換(SQLServer，Oracle不知道)DEGREES：弧度-角度RADIANS：角度-弧度數(shù)值間比較18. 求集合最大值S:select max(value) value from (select 1 valueunionselect -2 valueunionselect 4 valueunionselect 3 value)aO:select greatest(1,-2,4,3) value fr

6、om dual19. 求集合最小值S:select min(value) value from (select 1 valueunionselect -2 valueunionselect 4 valueunionselect 3 value)aO:select least(1,-2,4,3) value from dual20.如何處理null值(F2中的null以10代替)S:select F1,IsNull(F2,10) value from TblO:select F1,nvl(F2,10) value from Tbl數(shù)值間比較21.求字符序號(hào)S:select ascii(a) va

7、lueO:select ascii(a) value from dual22.從序號(hào)求字符S:select char(97) valueO:select chr(97) value from dual23.連接S:select 11+22+33 valueO:select CONCAT(11,22)|33 value from dual23.子串位置 -返回3S:select CHARINDEX(s,sdsq,2) value O:select INSTR(sdsq,s,2) value from dual23.模糊子串的位置 -返回2,參數(shù)去掉中間%則返回7S:select patindex

8、(%d%q%,sdsfasdqe) value O:oracle沒(méi)發(fā)現(xiàn)，但是instr可以通過(guò)第四霾問(wèn)刂瞥魷執(zhí)問(wèn)?BRselect INSTR(sdsfasdqe,sd,1,2) value from dual 返回624.求子串S:select substring(abcd,2,2) value O:select substr(abcd,2,2) value from dual25.子串代替 返回aijklmnefS:Select STUFF(abcdef, 2, 3, ijklmn) valueO:Select Replace(abcdef, bcd, ijklmn) value from

9、 dual26.子串全部替換S:沒(méi)發(fā)現(xiàn)O:select Translate(fasdbfasegas,fa,我 ) value from dual27.長(zhǎng)度S:len,datalengthO:length28.大小寫轉(zhuǎn)換 lower,upper29.單詞首字母大寫S:沒(méi)發(fā)現(xiàn)O:select INITCAP(abcd dsaf df) value from dual30.左補(bǔ)空格（LPAD的第一個(gè)參數(shù)為空格則同space函數(shù)）S:select space(10)+abcd valueO:select LPAD(abcd,14) value from dual31.右補(bǔ)空格（RPAD的第一個(gè)參數(shù)為

10、空格則同space函數(shù)）S:select abcd+space(10) valueO:select RPAD(abcd,14) value from dual32.刪除空格S:ltrim,rtrimO:ltrim,rtrim,trim33. 重復(fù)字符串S:select REPLICATE(abcd,2) value O:沒(méi)發(fā)現(xiàn)34.發(fā)音相似性比較(這兩個(gè)單詞返回值一樣，發(fā)音相同)S:Select SOUNDEX (Smith), SOUNDEX (Smythe)O:Select SOUNDEX (Smith), SOUNDEX (Smythe) from dualSQLServer中用Sele

11、ct DIFFERENCE(Smithers, Smythers) 比較soundex的差返回0-4，4為同音，1最高日期函數(shù)35.系統(tǒng)時(shí)間S:select getdate() valueO:select sysdate value from dual36.前后幾日直接與整數(shù)相加減37.求日期S:select convert(char(10),getdate(),20) valueO:select trunc(sysdate) value from dualselect to_char(sysdate,yyyy-mm-dd) value from dual38.求時(shí)間S:select conv

12、ert(char(8),getdate(),108) valueO:select to_char(sysdate,hh24:mm:ss) value from dual39.取日期時(shí)間的其他部分S:DATEPART 和 DATENAME 函數(shù) （第一個(gè)參數(shù)決定） O:to_char函數(shù) 第二個(gè)參數(shù)決定參數(shù)下表需要補(bǔ)充year yy, yyyy quarter qq, q (季度)month mm, m (m O無(wú)效)dayofyear dy, y (O表星期)day dd, d (d O無(wú)效)week wk, ww (wk O無(wú)效)weekday dw (O不清楚)Hour hh,hh12,h

13、h24 (hh12,hh24 S無(wú)效)minute mi, n (n O無(wú)效)second ss, s (s O無(wú)效)millisecond ms (O無(wú)效)40.當(dāng)月最后一天S:不知道O:select LAST_DAY(sysdate) value from dual41.本星期的某一天（比如星期日）S:不知道O:Select Next_day(sysdate,7) vaule FROM DUAL;42.字符串轉(zhuǎn)時(shí)間S:可以直接轉(zhuǎn)或者select cast(2004-09-08as datetime) valueO:Select To_date(2004-01-05 22:09:38,yyy

14、y-mm-dd hh24-mi-ss) vaule FROM DUAL;43.求兩日期某一部分的差（比如秒）S:select datediff(ss,getdate(),getdate()+12.3) valueO:直接用兩個(gè)日期相減（比如d1-d2=12.3）Select (d1-d2)*24*60*60 vaule FROM DUAL;44.根據(jù)差值求新的日期（比如分鐘）S:select dateadd(mi,8,getdate() valueO:Select sysdate+8/60/24 vaule FROM DUAL;45.求不同時(shí)區(qū)時(shí)間S:不知道O:Select New_time(

15、sysdate,ydt,gmt ) vaule FROM DUAL;時(shí)區(qū)參數(shù),北京在東8區(qū)應(yīng)該是YdtAST ADT 大西洋標(biāo)準(zhǔn)時(shí)間BST BDT 白令海標(biāo)準(zhǔn)時(shí)間CST CDT 中部標(biāo)準(zhǔn)時(shí)間EST EDT 東部標(biāo)準(zhǔn)時(shí)間GMT 格林尼治標(biāo)準(zhǔn)時(shí)間HST HDT 阿拉斯加夏威夷標(biāo)準(zhǔn)時(shí)間MST MDT 山區(qū)標(biāo)準(zhǔn)時(shí)間NST 紐芬蘭標(biāo)準(zhǔn)時(shí)間PST PDT 太平洋標(biāo)準(zhǔn)時(shí)間YST YDT YUKON標(biāo)準(zhǔn)時(shí)間配置 SQL Server 數(shù)據(jù)庫(kù)EXEC sp_dboption pubs, read only, True此選項(xiàng)把數(shù)據(jù)庫(kù) “pubs” 設(shè)置為只讀。EXEC sp_dboption pubs autos

16、hrink true此選項(xiàng)把符合條件的“pubs” 數(shù)據(jù)庫(kù)文件設(shè)置為自動(dòng)周期性收縮。EXEC sp_dboption pubs single user此命令每次只允許一個(gè)用戶訪問(wèn)數(shù)據(jù)庫(kù)。DBCC SHRINKDATABASE(PUBS, 10)會(huì)減小“pubs”數(shù)據(jù)庫(kù)中文件的大小，并允許有 10% 的可用空間。使用 T-SQL 創(chuàng)建表 create table MyTable ( stdID int, stdName varchar(50) )自定義數(shù)據(jù)類型 EXEC sp_addtype City, nvarchar(15), NULLEXEC sp_addtype PostCode, nv

17、archar(6), NULLEXEC sp_addtype NCode, nvarchar(18), NULL刪除自定義數(shù)據(jù)類型EXEC sp_droptype city使用 T-SQL 創(chuàng)建表CREATE TABLE Categories ( CategoryID int IDENTITY(1,1), CategoryName nvarchar(15) NOT NULL, Description ntext NULL, Picture image NULL)實(shí)體完整性實(shí)現(xiàn) l 主鍵約束CREATE TABLE jobs(Job_id smallint PRIMARY KEY,job_des

18、c varchar(50) NOT NULL)l 唯一約束CREATE TABLE jobs(Job_id smallint UNIQUE)l 標(biāo)識(shí)列CREATE TABLE jobs(Job_id smallint IDENTIRY（2,1） PRIMARY KEY)l Uniqueidentifier數(shù)據(jù)類型和NEWID 函數(shù)CREATE TABLE Customer (CustID uniqueidentifier NOT NULL DEFAULT NEWID(),CustName char(30) NOT NULL)INSERT Customer VALUES (NEWID(),ASB

19、)l 引用完整性實(shí)現(xiàn) ALTER TABLE dbo.Orders ADD CONSTRAINT FK_Orders_Customers FOREIGN KEY (CustomerID) REFERENCES dbo.Customers(CustomerID)l 更新表結(jié)構(gòu)ALTER TABLE MyTable ALTER COLUMN NullCOl NVARCHAR(20) NOT NULLALTER TABLE jobs ADD HIRE_DATE DATETIMEALTER TABLE Doc_ED DROP COLUMN Column_BALTER TABLE Doc_ED WITH

20、 NOCHECK ADD CONSTRAINT Exd_Check CHECK (Column_a 1) l 在已有字段中增加標(biāo)識(shí)約束時(shí)，必須先刪除該字段，再新建字段。alter table mytable drop column userid alter table mytable add userid int identity(1,1)l 刪除表DROP TABLE Airlines_Masterl DEFAULT約束USE NorthwindCREATE TABLE ABC (ASD int Default 8, ASDE varchar(20) Default UNKNOWN)USE

21、NorthwindALTER TABLE dbo.Customers ADD CONSTRAINT DF_contactname DEFAULT UNKNOWN FOR ContactName l CHECK約束CREATE TABLE ABCD (ASD int CHECK(ASD 01-01-1900 AND BirthDate 01-01-2010)PRIMARY KEY約束CREATE TABLE AWC (ASD int CHECK(ASD 100) PRIMARY KEY,ASDE varchar(80) Default UNKNOWN)USE Northwind ALTER TA

22、BLE Customers ADD CONSTRAINT PK_Customers PRIMARY KEY (CustomerID)l UNIQUE約束CREATE TABLE AAC (ASD int CHECK(ASD 100) PRIMARY KEY,ASDE int UNIQUE)USE NorthwindALTER TABLE Suppliers ADD CONSTRAINT U_CompanyName UNIQUE (CompanyName)l FOREIGN KEY約束CREATE TABLE ACC (ASD int CHECK(ASD + type As MyTitle FR

23、OM titles3. 聚合函數(shù)SELECT productid ,SUM(quantity) AS total_quantity FROM orderhist GROUP BY productid顯示所有type的值，并按type分組求平均值SELECT type, AVG(price) FROM titles WHERE royalty = 10 GROUP BY ALL type 條件中帶有聚合函數(shù)的，要用Having 子句SELECT productid, SUM(quantity) AS total_quantity FROM orderhistGROUP BY productid

24、HAVING SUM(quantity)=304. 模糊查詢 WHERE companyname LIKE %Restaurant%WHERE fax IS NULLWHERE country IN (Japan, Italy)WHERE unitprice BETWEEN 10 AND 201. 說(shuō)明：復(fù)制表(只復(fù)制結(jié)構(gòu),源表名：a 新表名：b) SQL: select * into b from a where 11 2.說(shuō)明：拷貝表(拷貝數(shù)據(jù),源表名：a 目標(biāo)表名：b) SQL: insert into b(a, b, c) select d,e,f from b; 3.說(shuō)明：顯示文章、

25、提交人和最后回復(fù)時(shí)間 SQL: select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b 4.說(shuō)明：外連接查詢(表名1：a 表名2：b) SQL: select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUTER JOIN b ON a.a = b.c 5.說(shuō)明：日程安排提前五分鐘提醒 SQL: select * from 日程安排 where datediff(minute,

26、f開(kāi)始時(shí)間,getdate()5 6.說(shuō)明：兩張關(guān)聯(lián)表，刪除主表中已經(jīng)在副表中沒(méi)有的信息 SQL: delete from info where not exists ( select * from infobz where info.infid=infobz.infid ) 說(shuō)明：- SQL: SELECT A.NUM, A.NAME, B.UPD_DATE, B.PREV_UPD_DATE FROM TABLE1, (SELECT X.NUM, X.UPD_DATE, Y.UPD_DATE PREV_UPD_DATE FROM (SELECT NUM, UPD_DATE, INBOUND_

27、QTY, STOCK_ONHAND FROM TABLE2 WHERE TO_CHAR(UPD_DATE,YYYY/MM) = TO_CHAR(SYSDATE, YYYY/MM) X, (SELECT NUM, UPD_DATE, STOCK_ONHAND FROM TABLE2 WHERE TO_CHAR(UPD_DATE,YYYY/MM) = TO_CHAR(TO_DATE(TO_CHAR(SYSDATE, YYYY/MM) | /01,YYYY/MM/DD) - 1, YYYY/MM) ) Y, WHERE X.NUM = Y.NUM （+） AND X.INBOUND_QTY + NV

28、L(Y.STOCK_ONHAND,0) X.STOCK_ONHAND ) B WHERE A.NUM = B.NUM 說(shuō)明：- SQL: select * from studentinfo where not exists(select * from student where studentinfo.id=student.id) and 系名稱=&strdepartmentname& and 專業(yè)名稱=&strprofessionname& order by 性別,生源地,高考總成績(jī) 7.說(shuō)明： 從數(shù)據(jù)庫(kù)中去一年的各單位電話費(fèi)統(tǒng)計(jì)(電話費(fèi)定額賀電化肥清單兩個(gè)表來(lái)源） SQL: SELECT

29、a.userper, a.tel, a.standfee, TO_CHAR(a.telfeedate, yyyy) AS telyear, SUM(decode(TO_CHAR(a.telfeedate, mm), 01, a.factration) AS JAN, SUM(decode(TO_CHAR(a.telfeedate, mm), 02, a.factration) AS FRI, SUM(decode(TO_CHAR(a.telfeedate, mm), 03, a.factration) AS MAR, SUM(decode(TO_CHAR(a.telfeedate, mm),

30、04, a.factration) AS APR, SUM(decode(TO_CHAR(a.telfeedate, mm), 05, a.factration) AS MAY, SUM(decode(TO_CHAR(a.telfeedate, mm), 06, a.factration) AS JUE, SUM(decode(TO_CHAR(a.telfeedate, mm), 07, a.factration) AS JUL, SUM(decode(TO_CHAR(a.telfeedate, mm), 08, a.factration) AS AGU, SUM(decode(TO_CHAR

31、(a.telfeedate, mm), 09, a.factration) AS SEP, SUM(decode(TO_CHAR(a.telfeedate, mm), 10, a.factration) AS OCT, SUM(decode(TO_CHAR(a.telfeedate, mm), 11, a.factration) AS NOV, SUM(decode(TO_CHAR(a.telfeedate, mm), 12, a.factration) AS DEC FROM (SELECT a.userper, a.tel, a.standfee, b.telfeedate, b.fact

32、ration FROM TELFEESTAND a, TELFEE b WHERE a.tel = b.telfax) a GROUP BY a.userper, a.tel, a.standfee, TO_CHAR(a.telfeedate, yyyy) 8.說(shuō)明：四表聯(lián)查問(wèn)題： SQL: select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where 9.說(shuō)明：得到表中最小的未使用的ID號(hào) SQL: SELECT (CASE WHEN EXIST

33、S(SELECT * FROM Handle b WHERE b.HandleID = 1) THEN MIN(HandleID) + 1 ELSE 1 END) as HandleID FROM Handle WHERE NOT HandleID IN (SELECT a.HandleID - 1 FROM Handle a)9.SQL語(yǔ)句技巧9.1、一個(gè)SQL語(yǔ)句的問(wèn)題:行列轉(zhuǎn)換select * from v_temp上面的視圖結(jié)果如下:user_name role_name系統(tǒng)管理員 管理員 feng 管理員 feng 一般用戶 test 一般用戶 想把結(jié)果變成這樣:user_name

34、role_name系統(tǒng)管理員 管理員 feng 管理員,一般用戶 test 一般用戶=create table a_test(name varchar(20),role2 varchar(20)insert into a_test values(李,管理員)insert into a_test values(張,管理員)insert into a_test values(張,一般用戶)insert into a_test values(常,一般用戶)create function join_str(content varchar(100)returns varchar(2000)asbegin

35、declare str varchar(2000)set str=select str=str+,+rtrim(role2) from a_test where name=contentselect str=right(str,len(str)-1)return strendgo-調(diào)用：select name,dbo.join_str(name) role2 from a_test group by name-select distinct name,dbo.uf_test(name) from a_test9.2、求助！快速比較結(jié)構(gòu)相同的兩表結(jié)構(gòu)相同的兩表，一表有記錄3萬(wàn)條左右，一表有記錄2

36、萬(wàn)條左右，我怎樣快速查找兩表的不同記錄？=給你一個(gè)測(cè)試方法，從northwind中的orders表取數(shù)據(jù)。select * into n1 from ordersselect * into n2 from ordersselect * from n1select * from n2-添加主鍵，然后修改n1中若干字段的若干條alter table n1 add constraint pk_n1_id primary key (OrderID)alter table n2 add constraint pk_n2_id primary key (OrderID)select OrderID fro

37、m (select * from n1union select * from n2) a group by OrderID having count(*) 1應(yīng)該可以，而且將不同的記錄的ID顯示出來(lái)。下面的適用于雙方記錄一樣的情況，select * from n1 where orderid in(select OrderID from (select * from n1union select * from n2) a group by OrderID having count(*) 1) 至于雙方互不存在的記錄是比較好處理的-刪除n1,n2中若干條記錄delete from n1 wher

38、e orderID in (10728,10730)delete from n2 where orderID in (11000,11001)-*- 雙方都有該記錄卻不完全相同select * from n1 where orderid in(select OrderID from (select * from n1union select * from n2) a group by OrderID having count(*) 1)union-n2中存在但在n1中不存的在10728,10730select * from n1 where OrderID not in (select Ord

39、erID from n2)union-n1中存在但在n2中不存的在11000,11001select * from n2 where OrderID not in (select OrderID from n1)9.3、四種方法取表里n到m條紀(jì)錄：1.select top m * into 臨時(shí)表(或表變量) from tablename order by columnname - 將top m筆插入set rowcount nselect * from 表變量 order by columnname desc2.select top n * from (select top m * from

40、 tablename order by columnname) aorder by columnname desc3.如果tablename里沒(méi)有其他identity列，那么：select identity(int) id0,* into #temp from tablename取n到m條的語(yǔ)句為：select * from #temp where id0 =n and id0 1exec(sql)open cur_rows fetch cur_rows into id,max while fetch_status=0 begin select max = max -1 set rowcoun

41、t max select type = xtype from syscolumns where id=object_id(t_name) and name=f_keyif type=56select sql = delete from +t_name+ where + f_key+ = + id if type=167select sql = delete from +t_name+ where + f_key+ = + id + exec(sql)fetch cur_rows into id,max end close cur_rows deallocate cur_rowsset rowc

42、ount 0endselect * from systypesselect * from syscolumns where id = object_id(a_dist)9.4.查詢數(shù)據(jù)的最大排序問(wèn)題（只能用一條語(yǔ)句寫） CREATE TABLE hard (qu char (11) ,co char (11) ,je numeric(3, 0) insert into hard values (A,1,3)insert into hard values (A,2,4)insert into hard values (A,4,2)insert into hard values (A,6,9)in

43、sert into hard values (B,1,4)insert into hard values (B,2,5)insert into hard values (B,3,6)insert into hard values (C,3,4)insert into hard values (C,6,7)insert into hard values (C,2,3)要求查詢出來(lái)的結(jié)果如下：qu co je A 6 9A 2 4B 3 6B 2 5C 6 7C 3 4就是要按qu分組，每組中取je最大的前2位！而且只能用一句sql語(yǔ)句！select * from hard a where je

44、in (select top 2 je from hard b where a.qu=b.qu order by je) 9.5.求刪除重復(fù)記錄的sql語(yǔ)句？ 怎樣把具有相同字段的紀(jì)錄刪除，只留下一條。例如，表test里有id,name字段如果有name相同的記錄 只留下一條，其余的刪除。name的內(nèi)容不定，相同的記錄數(shù)不定。有沒(méi)有這樣的sql語(yǔ)句？=A:一個(gè)完整的解決方案：將重復(fù)的記錄記入temp1表:select 標(biāo)志字段id,count(*) into temp1 from 表名group by 標(biāo)志字段idhaving count(*)12、將不重復(fù)的記錄記入temp1表:insert

45、 temp1select 標(biāo)志字段id,count(*) from 表名group by 標(biāo)志字段idhaving count(*)=13、作一個(gè)包含所有不重復(fù)記錄的表：select * into temp2 from 表名where 標(biāo)志字段id in(select 標(biāo)志字段id from temp1)4、刪除重復(fù)表:delete 表名5、恢復(fù)表：insert 表名select * from temp26、刪除臨時(shí)表:drop table temp1drop table temp2=B:create table a_dist(id int,name varchar(20)insert int

46、o a_dist values(1,abc)insert into a_dist values(1,abc)insert into a_dist values(1,abc)insert into a_dist values(1,abc)exec up_distinct a_dist,idselect * from a_distcreate procedure up_distinct(t_name varchar(30),f_key varchar(30)-f_key表示是分組字段即主鍵字段asbegindeclare max integer,id varchar(30) ,sql varcha

47、r(7999) ,type integerselect sql = declare cur_rows cursor for select +f_key+ ,count(*) from +t_name + group by +f_key + having count(*) 1exec(sql)open cur_rows fetch cur_rows into id,max while fetch_status=0 begin select max = max -1 set rowcount max select type = xtype from syscolumns where id=obje

48、ct_id(t_name) and name=f_keyif type=56select sql = delete from +t_name+ where + f_key+ = + id if type=167select sql = delete from +t_name+ where + f_key+ = + id + exec(sql)fetch cur_rows into id,max end close cur_rows deallocate cur_rowsset rowcount 0endselect * from systypesselect * from syscolumns

49、 where id = object_id(a_dist)10.1. 行列轉(zhuǎn)換-普通 假設(shè)有張學(xué)生成績(jī)表(CJ)如下 Name Subject Result 張三 語(yǔ)文 80 張三 數(shù)學(xué) 90 張三 物理 85 李四 語(yǔ)文 85 李四 數(shù)學(xué) 92 李四 物理 82 想變成 姓名 語(yǔ)文 數(shù)學(xué) 物理 張三 80 90 85 李四 85 92 82 declare sql varchar(4000) set sql = select Name select sql = sql + ,sum(case Subject when +Subject+ then Result end) +Subject+

50、from (select distinct Subject from CJ) as a select sql = sql+ from test group by name exec(sql) 10.2. 行列轉(zhuǎn)換-合并 有表A, id pid 1 1 1 2 1 3 2 1 2 2 3 1 如何化成表B: id pid 1 1,2,3 2 1,2 3 1 創(chuàng)建一個(gè)合并的函數(shù) create function fmerg(id int) returns varchar(8000) as begin declare str varchar(8000) set str= select str=str+

51、,+cast(pid as varchar) from 表A where id=id set str=right(str,len(str)-1) return(str) End go -調(diào)用自定義函數(shù)得到結(jié)果 select distinct id,dbo.fmerg(id) from 表A 10.3. 如何取得一個(gè)數(shù)據(jù)表的所有列名 方法如下：先從SYSTEMOBJECT系統(tǒng)表中取得數(shù)據(jù)表的SYSTEMID,然后再SYSCOLUMN表中取得該數(shù)據(jù)表的所有列名。 SQL語(yǔ)句如下： declare objid int,objname char(40) set objname = tablename

52、select objid = id from sysobjects where id = object_id(objname) select Column_name = name from syscolumns where id = objid order by colid 是不是太簡(jiǎn)單了？ 呵呵 不過(guò)經(jīng)常用阿. 10.4. 通過(guò)SQL語(yǔ)句來(lái)更改用戶的密碼 修改別人的,需要sysadmin role EXEC sp_password NULL, newpassword, User 如果帳號(hào)為SA執(zhí)行EXEC sp_password NULL, newpassword, sa 10.5. 怎么判

53、斷出一個(gè)表的哪些字段不允許為空？ select COLUMN_NAME from INFORMATION_SCHEMA.COLUMNS where IS_NULLABLE=NO and TABLE_NAME=tablename 10.6. 如何在數(shù)據(jù)庫(kù)里找到含有相同字段的表？ a. 查已知列名的情況 SELECT as TableName, as columnname From syscolumns a INNER JOIN sysobjects b ON a.id=b.id AND b.type=U AND =你的字段名字 b. 未知列名查所有在不同表出現(xiàn)過(guò)的列名 Select As tab

54、lename, As columnname From syscolumns s1, sysobjects o Where s1.id = o.id And o.type = U And Exists ( Select 1 From syscolumns s2 Where = And s1.id s2.id ) 10.7. 查詢第xxx行數(shù)據(jù) 假設(shè)id是主鍵： select * from (select top xxx * from yourtable) aa where not exists(select 1 from (select top xxx-1 * from yourtable) b

55、b where aa.id=bb.id) 如果使用游標(biāo)也是可以的 fetch absolute number from cursor_name 行數(shù)為絕對(duì)行數(shù) 10.8. SQL Server日期計(jì)算 a. 一個(gè)月的第一天 SELECT DATEADD(mm, DATEDIFF(mm,0,getdate(), 0) b. 本周的星期一 SELECT DATEADD(wk, DATEDIFF(wk,0,getdate(), 0) c. 一年的第一天 SELECT DATEADD(yy, DATEDIFF(yy,0,getdate(), 0) d. 季度的第一天 SELECT DATEADD(qq

56、, DATEDIFF(qq,0,getdate(), 0) e. 上個(gè)月的最后一天 SELECT dateadd(ms,-3,DATEADD(mm, DATEDIFF(mm,0,getdate(), 0) f. 去年的最后一天 SELECT dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate(), 0) g. 本月的最后一天 SELECT dateadd(ms,-3,DATEADD(mm, DATEDIFF(m,0,getdate()+1, 0) h. 本月的第一個(gè)星期一 select DATEADD(wk, DATEDIFF(wk,0, datea

57、dd(dd,6-datepart(day,getdate(),getdate() ), 0) i. 本年的最后一天 SELECT dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate()+1, 0)。 11.1.獲取表結(jié)構(gòu)把 sysobjects 替換 成 tablename 即可 SELECT CASE IsNull(I.name, ) When Then Else * End as IsPK, Object_Name(A.id) as t_name, A.name as c_name, IsNull(SubString(M.text, 1, 254

58、), ) as pbc_init, T.name as F_DataType, CASE IsNull(TYPEPROPERTY(T.name, Scale), ) WHEN Then Cast(A.prec as varchar) ELSE Cast(A.prec as varchar) + , + Cast(A.scale as varchar) END as F_Scale, A.isnullable as F_isNullAble FROM Syscolumns as A JOIN Systypes as T ON (A.xType = T.xUserType AND A.Id = O

59、bject_id(sysobjects) ) LEFT JOIN ( SysIndexes as I JOIN Syscolumns as A1 ON ( I.id = A1.id and A1.id = object_id(sysobjects) and (I.status & 0 x800) = 0 x800 AND A1.colid 0 then else end) N主鍵, N類型, a.length N占用字節(jié)數(shù), COLUMNPROPERTY(a.id,PRECISION) as N長(zhǎng)度, isnull(COLUMNPROPERTY(a.id,Scale),0) as N小數(shù)位數(shù),

60、 (case when a.isnullable=1 then else end) N允許空, isnull(e.text,) N默認(rèn)值, isnull(g.value,) AS N字段說(shuō)明 FROM syscolumns a left join systypes b on a.xtype=b.xusertype inner join sysobjects d on a.id=d.id and d.xtype=U and dtproperties left join syscomments e on a.cdefault=e.id left join sysproperties g on a.