SQL 根據定義的優先級查找匹配記錄

Question

我必須建立一個邏輯來更新一列SC_LEVI_LVL IN GCC_MAST.CLNT_MAST基於以下條件找到的匹配：

（我只是在查看 select 子句，稍后我將使用 informatica 中的更新策略對其進行更新）

需要在三個表上進行聯接：

對於優先級 1，需要在以下兩個表上進行連接：

GCC_LANDING.CB_AT_LIS CB
    GCC_MAST.CLNT_MAST TM

對於優先級 2，需要在以下 3 個表上進行連接：

GCC_LANDING.CB_AT_LIS CB
GCC_MAST.CLNT_MAST TM
GCC_LANDING.GRID_MATRIX GM

優先級 1：

CB.REL_COUNTRY=TM.REL_COUNTRY
AND CB.GRID=TM.GRID
WHERE TM.SCH_LEG_ENTY NOT LIKE '%BASE%'
AND CB.LAT='Y'

預期結果：

優先級 2：

CB.GRID=GM.GRID
AND CB.REL_COUNTRY=TM.REL_COUNTRY
AND GM.SUR_GRD=TM.GRID
WHERE TM.SCH_LEG_ENTY NOT LIKE '%BASE%'
AND TM.CUS LIKE '% BGM%'
AND CB.GRID <> TM.GRID
AND TM.CUST_FLG='N'

預期成績：

（如果多條記錄按 ROW_NUMBER=1 找到分區）

我能想到的就是將所有這些都放在一個查詢中，並在所有表上加入連接（結合 P1 和 P2），然后在開頭添加一個 case 語句。 但是，我認為這不是正確的方法。

有人可以指導我如何進行嗎？ 我對此很陌生，我會用我想出的任何東西來更新帖子。

期望的結果應該是 SC_LEVI_LVL IN GCC_MAST.CLNT_MAST 首先基於 P1 的值，如果 P1 不匹配，則 P2

謝謝！

Answer 1

-- here is the combination of the two - priority_one and priority_two
WITH
    landing As
        (
            Select 'NZ' "REL_COUNTRY", 12345 "GRID", 'Y' "LAT", 'ABC' "SC_LEVI_LVL" From Dual
          UNION
            Select 'MO' "REL_COUNTRY", 44444 "GRID", 'Y' "LAT", 'XYZ' "SC_LEVI_LVL" From Dual
          UNION
            Select 'PH' "REL_COUNTRY", 55555 "GRID", 'Y' "LAT", 'ERT' "SC_LEVI_LVL" From Dual
          UNION
            Select 'PH' "REL_COUNTRY", 78786 "GRID", 'Y' "LAT", 'ERT' "SC_LEVI_LVL" From Dual
        ),
    clnt As
        (
            Select 'ZA' "REL_COUNTRY", 56565 "GRID", 'HBASEU' "SCH_LEG_ENTY", 'TFGD' "CUS", 'N' "CUST_FLG" From Dual
          UNION
            Select 'NZ' "REL_COUNTRY", 12345 "GRID", 'DFGT' "SCH_LEG_ENTY", 'HBGM' "CUS", 'N' "CUST_FLG" From Dual
          UNION
            Select 'MO' "REL_COUNTRY", 44444 "GRID", 'DFGTU' "SCH_LEG_ENTY", 'HBGM' "CUS", 'N' "CUST_FLG" From Dual
          UNION
            Select 'PH' "REL_COUNTRY", 99999 "GRID", 'DFGTU' "SCH_LEG_ENTY", 'HBGM' "CUS", 'N' "CUST_FLG" From Dual
        ),
    matrix As
        ( Select 99999 "SUR_GRID", 78786 "GRID" From Dual ),
    priority_one As 
        (
            SELECT
                'ONE' "WHICH_ONE",
                cb.REL_COUNTRY "REL_COUNTRY",
                cb.GRID "GRID",
                cb.LAT "LAT",
                cb.SC_LEVI_LVL "SC_LEVI_LVL"
            FROM
                landing cb
            INNER JOIN
                clnt tm ON(CB.REL_COUNTRY=TM.REL_COUNTRY And cb.GRID = tm.GRID)
            WHERE 
                tm.SCH_LEG_ENTY NOT LIKE '%BASE%' And 
                CB.LAT = 'Y'
        ),
    priority_two As
        (
            SELECT
                'TWO' "WHICH_ONE",
                cb.REL_COUNTRY "REL_COUNTRY",
                cb.GRID "GRID",
                cb.LAT "LAT",
                cb.SC_LEVI_LVL "SC_LEVI_LVL"
            FROM
                matrix gm
            INNER JOIN
                landing cb ON(cb.GRID = gm.GRID)
            INNER JOIN
                clnt tm ON(cb.REL_COUNTRY = tm.REL_COUNTRY And gm.SUR_GRID = tm.GRID)
            WHERE 
                tm.SCH_LEG_ENTY NOT LIKE '%BASE%' And 
                cb.GRID <> tm.GRID And 
                tm.CUST_FLG = 'N'
        )
    SELECT WHICH_ONE, REL_COUNTRY, GRID, LAT, SC_LEVI_LVL From priority_one 
  UNION ALL 
    SELECT WHICH_ONE, REL_COUNTRY, GRID, LAT, SC_LEVI_LVL FROM priority_two
--
-- Result:
--
-- WHICH_ONE REL_COUNTRY       GRID LAT SC_LEVI_LVL
-- ONE       MO               44444 Y   XYZ       
-- ONE       NZ               12345 Y   ABC       
-- TWO       PH               78786 Y   ERT