如果您可以在没有 PL/SQL 的情况下获得您的查询 - 只是简单的 SQL，那会怎么样？
假设您的两个表如下所示：
CREATE TABLE
A_TBL_1 (ID, TXT, SOME_COL, COL_1_T1, DATE_T1) AS
(
SELECT 1, 'TEXT for ID 1', 'Something else 1 in tbl_1', 'X', To_Date('20221231', 'yyyymmdd') From Dual Union All
SELECT 2, 'TEXT for ID 2', 'Something else 2 in tbl_1', 'Y', To_Date('20221231', 'yyyymmdd') From Dual Union All
SELECT 3, 'TEXT for ID 3', 'Something else 3 in tbl_1', 'Z', To_Date('20221231', 'yyyymmdd') From Dual
);
CREATE TABLE
A_TBL_2 (ID, TXT, SOME_COL, COL_1_T2) AS
(
SELECT 11, 'TEXT for ID 11', 'Something else 11 in tbl_2', 'X' From Dual Union All
SELECT 12, 'TEXT for ID 12', 'Something else 12 in tbl_2', 'Y' From Dual Union All
SELECT 13, 'TEXT for ID 13', 'Something else 13 in tbl_2', 'X' From Dual
);
...并且您的规则设置如下
CREATE TABLE
A_RULE_TBL (RULE_ID, PAR_ID, PAR_EXPL, PAR_VAL) AS
(
SELECT 1, 1, 'A_TBL_1', 'a' FROM DUAL UNION ALL
SELECT 1, 2, 'A_TBL2', 'b' FROM DUAL UNION ALL
SELECT 1, 3, 'COL_1_T1', 'X' FROM DUAL UNION ALL
SELECT 1, 4, 'COL_1_T2', 'X' FROM DUAL UNION ALL
SELECT 1, 5, 'DATE_T1', '20221231' FROM DUAL UNION ALL
SELECT 2, 1, 'A_TBL_1', 'a' FROM DUAL UNION ALL
SELECT 2, 2, 'A_TBL_2', 'b' FROM DUAL UNION ALL
SELECT 2, 3, 'COL_1_T1', 'Y' FROM DUAL UNION ALL
SELECT 2, 4, 'COL_1_T2', 'Y' FROM DUAL UNION ALL
SELECT 2, 5, 'DATE_T1', '20221231' FROM DUAL
);
如果我们使用 CTE（命名参数）对规则进行 Pivot 和 Unpivot_
WITH
params AS
( Select *
From A_RULE_TBL
PIVOT (
Max(CASE WHEN PAR_ID = 1 THEN PAR_EXPL END) "SRC_TBL",
Max(CASE WHEN PAR_ID = 2 THEN PAR_EXPL END) "LKP_TBL",
Max(CASE WHEN PAR_ID = 3 THEN PAR_EXPL END) "SRC_COL",
Max(CASE WHEN PAR_ID = 4 THEN PAR_EXPL END) "LKP_COL",
Max(CASE WHEN PAR_ID = 5 THEN PAR_EXPL END) "DATE",
--
Max(CASE WHEN PAR_ID = 1 THEN PAR_VAL END) "SRC_TBL_VAL",
Max(CASE WHEN PAR_ID = 2 THEN PAR_VAL END) "LKP_TBL_VAL",
Max(CASE WHEN PAR_ID = 3 THEN PAR_VAL END) "SRC_COL_VAL",
Max(CASE WHEN PAR_ID = 4 THEN PAR_VAL END) "LKP_COL_VAL",
Max(CASE WHEN PAR_ID = 5 THEN PAR_VAL END) "DATE_VAL"
FOR RULE_ID IN(1 "ID1", 2 "ID2") )
UNPIVOT( (SRC_TBL, SRC_COL, LKP_TBL, LKP_COL, A_DATE, SRC_TBL_VAL, SRC_COL_VAL, LKP_TBL_VAL, LKP_COL_VAL, DATE_VAL)
FOR RULE_ID
IN (
(ID1_SRC_TBL, ID1_SRC_COL, ID1_LKP_TBL, ID1_LKP_COL, ID1_DATE, ID1_SRC_TBL_VAL, ID1_SRC_COL_VAL, ID1_LKP_TBL_VAL, ID1_LKP_COL_VAL, ID1_DATE_VAL ) as 1,
(ID2_SRC_TBL, ID2_SRC_COL, ID2_LKP_TBL, ID2_LKP_COL, ID2_DATE, ID2_SRC_TBL_VAL, ID2_SRC_COL_VAL, ID2_LKP_TBL_VAL, ID2_LKP_COL_VAL, ID2_DATE_VAL ) as 2 )
)
ORDER BY RULE_ID
)
--
-- R e s u l t
-- RULE_ID SRC_TBL SRC_COL LKP_TBL LKP_COL A_DATE SRC_TBL_VAL SRC_COL_VAL LKP_TBL_VAL LKP_COL_VAL DATE_VAL
-- ---------- -------- -------- -------- -------- -------- ----------- ----------- ----------- ----------- --------
-- 1 A_TBL_1 COL_1_T1 A_TBL_2 COL_1_T2 DATE_T1 a X b X 20221231
-- 2 A_TBL_1 COL_1_T1 A_TBL_2 COL_1_T2 DATE_T1 a Y b Y 20221231
结果数据集包含构建不同 sql 命令所需的一切。这里对于 RULE_ID = 1 将有用于左连接表和选择不匹配的行的 SQL。对于 RULE_ID = 2 匹配的行。
SELECT
'Select ' || SRC_TBL_VAL || '.' || SRC_COL || ', Count(*) "CNT" ' || Chr(10) ||
'From ' || SRC_TBL || ' ' || SRC_TBL_VAL || ' ' || Chr(10) ||
'Left Join ' || LKP_TBL || ' ' || LKP_TBL_VAL || ' ON(' || LKP_TBL_VAL || '.' || LKP_COL || ' = ' || SRC_TBL_VAL || '.' || SRC_COL || ')' || Chr(10) ||
'Where ' || LKP_TBL_VAL || '.' || LKP_COL || ' Is ' || CASE RULE_ID WHEN 2 THEN 'Not' ELSE '' END || ' Null ' || Chr(10) ||
'Group By ' || SRC_TBL_VAL || '.' || SRC_COL || ' ' || Chr(10) ||
'Order By Count(*) DESC' "SQL_COMMANDS"
FROM params
ORDER BY RULE_ID
/* R e s u l t :
SQL_COMMANDS
--------------------------------------------------
Select a.COL_1_T1, Count(*) "CNT"
From A_TBL_1 a
Left Join A_TBL_2 b ON(b.COL_1_T2 = a.COL_1_T1)
Where b.COL_1_T2 Is Null
Group By a.COL_1_T1
Order By Count(*) DESC
Select a.COL_1_T1, Count(*) "CNT"
From A_TBL_1 a
Left Join A_TBL_2 b ON(b.COL_1_T2 = a.COL_1_T1)
Where b.COL_1_T2 Is Not Null
Group By a.COL_1_T1
Order By Count(*) DESC
*/
如果针对上述示例数据运行第一个查询，结果为：
-- COL_1_T1 CNT
-- -------- ----------
-- Z 1
...而第二个结果为：
-- COL_1_T1 CNT
-- -------- ----------
-- X 2
-- Y 1