1. case when then

case end構成語法開始和結束

when 條件滿足執行 then 否則執行 else

case
  when ba.org is not null and ba.org = 'GD' then
   'GD'
  else
   'OL'
end "ORDER_SOURCE"

2. decode()

decode(表示式,結果1,表示式/結果…)

decode函式第一個為先決條件,其他欄位表示條件表示式或者結果,

select decode(1,2,3,4,5,1,7) r from dual;--返回值是7

decode(1,2,3,4) 返回值是4
 
 沒有滿足的情況取預設值 4
decode(1,1,3,4) 返回值是3

decode(crk.risklevel,
              1,
              'C1',
              2,
              'C2',
              3,
              'C3',
              4,
              'C4',
              5,
              'C5',
              'C1') "CUSTOMER_RISK_LEVEL"

where bsb.bankid =
 
 decode(t.tradechannel, 0, t.bankid, cc.bankid)

3. (+)

(+) 等同於 left join on , 如果沒有(+) 會過濾掉匹配不上的資料, 這裡只過濾掉 t表的,反之加了(+)就是加上 ba 表中沒有的資料.已 t為主,返回t中所有記錄

 where t.serialno = ba.serno(+)
   and t.custaccount = cc.custaccount(+)
   and t.account = c.account
   and t.issueid = i.issueid

4. to_date()

按照執行格式轉成日期型別.

to_date(bs.sysvalue, 'yyyymmdd')

5.to_number()

將欄位轉存成數值型別,該函式會剔除欄位值前面所有的0
例如 0000012358
to_number 之後 12358

to_number(rc.bancsno) "CUSTOMER_ID"

6.to_char()

將時間型別欄位按照格式轉成字元型欄位

to_char(t.tradedate, 'YYYYMMDD') "ESTABLISH_DATE"

7.nvl()

判斷欄位值是否為空,是的話去候選欄位,否則返回fp.price

nvl(fp.price, p.offerprice) "NAV"

8.trunc()

TRUNC函式返回以指定元素格式截去一部分的日期值。

 trunc(i.recorddate) >= trunc(to_date(bs.sysvalue, 'yyyymmdd'))

案例程式碼

實際專案SQL程式碼

nvl(to_char(case
             when t.attr = 0 and f.islockperiodissue != 1 and
                    t.trancode not in (0, 1, 2) then
                null
               else
                decode(ba.fudate, null, t.tradedate, ba.fudate)
             end,
             'HHmmss'),
     to_char(t.tradedate, 'hhmmss')) "ESTABLISH_TIME"

where t.serialno = ba.serno(+)
   and t.custaccount = cc.custaccount(+)
   and t.account = c.account
   and t.issueid = i.issueid
   and i.serialcode = f.serialcode(+)
   and bs.syscode = 'sys.date'
   and t.account = crk.account(+)
   and bsb.bankid = decode(t.tradechannel, 0, t.bankid, cc.bankid)
   and not ((t.trancode = 0 and t.state = 0 and
        trunc(i.recorddate) >= trunc(to_date(bs.sysvalue, 'yyyymmdd')) and
        i.state in (1, 4)) or
        (t.trancode = 2 and t.payamtdate is not null and t.state = 0 and
        trunc(t.payamtdate) <> trunc(to_date(bs.sysvalue, 'yyyymmdd'))))

decode(t.memo, '', '0000', '9999') "RETURN_CODE"