高手是怎樣煉成的:精妙SQL語句介紹
  如何從一位菜鳥蛻變成為高手,靈活使用的SQL語句是必不可少的。本文收集了部分比較經(jīng)典,常用的SQL語句供大家參考,希望對(duì)大家有所幫助。 
  說明: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 1<>1 
  說明: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; 
  說明:顯示文章、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 
  說明: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 OUT JOIN b ON a.a = b.c 
  說明:日程安排提前五分鐘提醒   
  SQL: select * from 日程安排 where datediff('minute',f開始時(shí)間,getdate())>5   
  說明:兩張關(guān)聯(lián)表,刪除主表中已經(jīng)在副表中沒有的信息 
  SQL:    
  delete from info where not exists ( select * from infobz where info.infid=infobz.infid 
  說明:-- 
  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_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 + NVL(Y.STOCK_ONHAND,0) <> X.STOCK_ONHAND B 
  WHERE A.NUM = B.NUM 
  說明:-- 
  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) 
  說明: 
  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)表來源) 
  SQL:   
  SELECT 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'), '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(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.factration 
   FROM TELFEESTAND a, TELFEE b 
   WHERE a.tel = b.telfax) a 
  GROUP BY a.userper, a.tel, a.standfee, TO_CHAR(a.telfeedate, 'yyyy') 
  說明:四表聯(lián)查問題:   
  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 ..... 
  說明:得到表中最小的未使用的ID號(hào) 
  SQL:  
  SELECT (CASE WHEN EXISTS(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)
關(guān)鍵詞:SQL語句
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