关于SQL的常用技巧

      本文章跟大家一起分享学习的是关于在学习ASP中，SQL的常用技巧，希望能对ASP初学者提供帮助。

      一.怎样删除一个表中某个字段重复的列呀,举个例子
      表[table1]

      SELECT DISTINCT id,, name
      INTO #t
      FROM table1 DELETE table1
      INSERT
      INTO table1
      SELECT *
      FROM #t

      SELECT 员工 FROM [Table] WHERE 员工 IN(SELECT 员工 FROM [Table] WHERE 技能='VB' ) AND 技能='PHP'

      insert into c(id,name,.....)
      select id,name,.....
      from a
      insert into c(id,name,.....)
      select max(id)+1,name,.....
      from b

      insert into c(name,.....)
      select name,.....
      from a
      insert into c(name,.....)
      select name,.....
      from b

      insert into [c] ([id] ,编号,自动编号)
      select [id],编号,自动编号 from [a]
      union
      select [id],编号,自动编号 from [b]

      ＜% '循环检测a表
      Set rs = Server.CreateObect("ADODB.RECORDSET")
      rs.open "select * from a order by id",conn,1,1
      Do while not rs.eof
      Call actAdd(rs("name")) '调用像b表添加内容的函数！
      rs.MoveNext
      Loop
      rs.Close
      Set rs = Nothing
      Sub actAdd(txt)
      Dim ts, sql
      sql = "insert into b(name) values('"& txt &"')"
      Set ts = Conn.Execute(sql)
      ts.Close
      Set ts = Nothing
      end Sub
      %＞

      ＜%
      dim arr_temp1,arr_temp2,arr_data
      set rs=conn.execute("select id,name,price,guige,changjia,baozhuang,danwei from a")
      arr_temp1=rs.getrows
      rs.close
      set rs=nothing
      set rs=conn.execute("select id,name,price,guige,changjia,danwei,xingzhi from b")
      arr_temp2=rs.getrows
      rs.close
      set rs=nothing
      rem 开始处理
      redim arr_data(ubound(arr_temp1,2)+ubound(arr_temp2,2),7)
      rem 把两个数组的内容复制进来
      这一部分自己写了做两个循环
      然后再存进数据库
      %＞

      SQL: select * into b from a where 1＜＞1

      SQL: insert into b(a, b, c) select d,e,f from b;

      SQL: select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) 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

      SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())＞5

      delete from info where not exists ( select * from infobz where info.infid=infobz.infid )

      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

      select * from studentinfo where not exists(select * from student where studentinfo.id=student.id) and 系名称='"&strdepartmentname&"' and 专业名称='"&strprofessionname&"' order by 性别,生源地,高考总成绩

      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')

      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 .....

      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)

      delete table
      where id not in
      (
      select max(id) from table group by col1,col2,col3...
      )

      select * from table where col1+','+col2+','...col5 in (
      select max(col1+','+col2+','...col5) from table
      where having count(*)＞1
      group by col1,col2,col3,col4
      )

      select * into #aa from table group by id1,id2,....
      delete table
      insert into table
      select * from #aa

      select identity(int,1,1) as id,* into #temp from ta
      delete #temp
      where id not in
      (
      select max(id) from # group by col1,col2,col3...
      )
      delete table ta
      inset into ta(...)
      select ..... from #temp

      alter table 表 add newfield int identity(1,1)
      delete 表
      where newfield not in
      (
      select min(newfield) from 表 group by 除newfield外的所有字段
      )
      alter table 表 drop column newfield