oracle sql中根据其他表中的计数重新启动rownumber

Question

我有两个没有公用键的表我想在没有笛卡尔连接的情况下对这两个表进行连接。 表 1 大约有 40,000 行（记录数在每天的生产中有所不同），而表 2 目前的计数为 80,000 行（记录数在每天的生产中有所不同）。

TABLE1 :- NAME_VALUES

NAME_VAL
--------
TOM
DICK
HARRY 

TABLE2 :- CUS_TABLE

CUS_ID
---------
401795480  
201134211 
137643082 
876450821 
777290153 
111035791 
579865552 

我想有一些像下面这样的输出

401795480 TOM
201134211 DICK
137643082 HARRY
876450821 DICK
777290153 HARRY
111035791 TOM
579865552 DICK

我的想法是为每个表分配行号。对于表 2，一旦达到表 1 的最大计数，我想重新启动行号，如下所示，但无法弄清楚我该如何执行

Table1
    NAME_VAL   TABLE1_RN 
    --------------------- 
    TOM          1
    DICK         2
    HARRY        3

Table2
    CUS_ID    TABLE2_RN
    --------------------
    401795480 1 
    201134211 2
    137643082 3
    876450821 1
    777290153 2
    111035791 3
    579865552 1 

现在我有了一个键，可以轻松映射以获取我需要的详细信息。

请建议是否有任何方法可以满足我的要求。

Answer 1

显示想法的规范（可能很慢）解决方案

这是一个在连接谓词上使用模运算符的相当慢的解决方案：

SELECT cus_id, name_val
FROM (
  SELECT cus_id, ROWNUM - 1 rn
  FROM cus_table
) c
JOIN (
  SELECT name_val, ROWNUM - 1 rn, MAX(ROWNUM) OVER() total
  FROM name_values
) n
ON n.rn = MOD(c.rn, n.total)
ORDER BY c.rn

以上产量

CUS_ID      NAME_VAL
--------------------
401795480   TOM
201134211   DICK
137643082   HARRY
876450821   TOM
777290153   DICK
111035791   HARRY
579865552   TOM

SQLFiddle here

使用 SQL 的更快解决方案

为了加快上述速度，您有多种选择，包括为c 和n 创建物化视图，或者在源表中预先计算n.rn - 1 和MOD(c.rn - 1, n.total) 的值，同时将这些预先计算好的表上的索引。

使用 PL/SQL 的更快解决方案

如果您被允许在您的系统中编写 PL/SQL，您显然可以为此使用 PIPELINED 函数：

CREATE TYPE rec AS OBJECT (
  cus_id NUMBER(18),
  name_val VARCHAR2(50)
);
/

CREATE TYPE tab AS TABLE OF rec;
/

CREATE OR REPLACE FUNCTION f RETURN tab PIPELINED AS
  TYPE name_vals IS TABLE OF name_values.name_val%type;
  v_name_vals name_vals;
BEGIN
  SELECT name_val
  BULK COLLECT INTO v_name_vals
  FROM name_values;

  FOR cus IN (SELECT cus_id, ROWNUM rn FROM cus_table)
  LOOP
    PIPE ROW(rec(cus.cus_id, v_name_vals(MOD(cus.rn - 1, v_name_vals.count) + 1)));
  END LOOP;
  RETURN;
END;
/

然后按如下方式使用该函数：

SELECT * FROM TABLE(f);

Answer 2

使用 SQL 模型子句，不需要连接操作。

select cus_id, name_val
  from (select cus_id,
               mod(row_number() over (order by 1) - 1, (select count(*) cnt from name_values)) + 1 rn
          from cus_table)
 model
   reference nv on (select name_val, rownum rn from name_values) dimension by (rn) measures (name_val)
   main cus
   dimension by (cus_id, rn)
   measures (cast((null) as varchar2(4000)) as name_val)
   rules upsert all
 (
   name_val[any, any] = nv.name_val[cv(rn)]
 );

还有一个示例执行：

SQL> WITH
  2    name_values (name_val) AS (
  3      SELECT 'TOM'   FROM dual UNION ALL
  4      SELECT 'DICK'  FROM dual UNION ALL
  5      SELECT 'HARRY' FROM dual
  6    ),
  7    cus_table (cus_id) AS (
  8      SELECT 401795480 FROM dual UNION ALL
  9      SELECT 201134211 FROM dual UNION ALL
 10      SELECT 137643082 FROM dual UNION ALL
 11      SELECT 876450821 FROM dual UNION ALL
 12      SELECT 777290153 FROM dual UNION ALL
 13      SELECT 111035791 FROM dual UNION ALL
 14      SELECT 579865552 FROM dual
 15    )
 16  select cus_id, name_val
 17    from (select cus_id,
 18                 mod(row_number() over (order by 1) - 1, (select count(*) cnt from name_values)) + 1 rn
 19            from cus_table)
 20   model
 21     reference nv on (select name_val, rownum rn from name_values) dimension by (rn) measures (name_val)
 22     main cus
 23     dimension by (cus_id, rn)
 24     measures (cast((null) as varchar2(4000)) as name_val)
 25     rules upsert all
 26   (
 27     name_val[any, any] = nv.name_val[cv(rn)]
 28   );
    CUS_ID NAME_VAL
---------- --------------------
 401795480 TOM
 876450821 TOM
 579865552 TOM
 201134211 DICK
 777290153 DICK
 137643082 HARRY
 111035791 HARRY
7 rows selected