具有易失性表和 CTE 的 Teradata 宏，用于将数据插入表中

Question

我需要先创建一个 teradata 宏来将信息提取到 volatile 表中，然后执行 CTE 从该 volatile 表中提取数据并插入到 teradata 表中，尝试了不同的方法都失败了，感谢帮助！

CREATE MACRO database.macro_insertion_tablename AS (

  CREATE VOLATILE TABLE vt AS
  (
     SELECT
       id, bu,
       CONCAT(TO_CHAR(comment_date, 'yyyy-mm-dd HH24:MI:SS'), ' ', action) AS full_action,
       ROW_NUMBER() OVER (PARTITION BY id ORDER BY date DESC) AS row_num, 
       COUNT(*) OVER (PARTITION BY id) as cnt
     FROM database.table1
  ) WITH DATA UNIQUE PRIMARY INDEX(id, row_num) ON COMMIT PRESERVE ROWS; 

  WITH RECURSIVE cte (id, bu, act, rn) AS
  (
     SELECT 
       id, bu
       ,CAST(full_action AS VARCHAR(5000)) AS full_action
       ,row_num
     FROM vt
     WHERE row_num = cnt

     UNION ALL

     SELECT
       vt.id, vt.bu 
       ,cte.act || ' / ' || vt.full_action
       ,vt.row_num
     FROM vt
     JOIN cte On vt.id = cte.id AND vt.row_num = cte.rn - 1
  )  

  INSERT INTO database.table (id, bu, full_action)
  SELECT id, bu, act
  FROM cte
  WHERE rn = 1;

  DROP TABLE vt; 
); 

Answer 1

DDL 必须是 Teradata 宏中的 only 语句。

作为解决方法，您可以切换到定义一次的 全局临时表，然后您只需将其插入/选择而不是 CREATE VOLATILE TABLE。

但在您的情况下，不需要临时表和低效的递归处理来获得“组连接”：

SELECT id, max(bu) -- maybe min(bu)?
   XmlAgg(Concat(To_Char(comment_date, 'yyyy-mm-dd HH24:MI:SS'), ' ', action)
          ORDER BY comment_date)  (VARCHAR(5000)) AS full_action
FROM database.table1
GROUP BY 1

会给你类似的结果。

Answer 2

要跟进我的 cmets，您应该能够在同一语句中定义多个 CTE。让RECURSIVE CTE 工作可能很棘手，但听起来这是可能的。也许是这样的：

CREATE MACRO database.macro_insertion_tablename AS (

  WITH vt (id, bu, full_action, row_num, cnt) AS
  (
     SELECT
       id, bu,
       CONCAT(TO_CHAR(comment_date, 'yyyy-mm-dd HH24:MI:SS'), ' ', action) AS full_action,
       ROW_NUMBER() OVER (PARTITION BY id ORDER BY date DESC) AS row_num, 
       COUNT(*) OVER (PARTITION BY id) as cnt
     FROM database.table1
  ),
  RECURSIVE cte (id, bu, act, rn) AS
  (
     SELECT 
       id, bu
       ,CAST(full_action AS VARCHAR(5000)) AS full_action
       ,row_num
     FROM vt
     WHERE row_num = cnt

     UNION ALL

     SELECT
       vt.id, vt.bu 
       ,cte.act || ' / ' || vt.full_action
       ,vt.row_num
     FROM vt
     JOIN cte On vt.id = cte.id AND vt.row_num = cte.rn - 1
  )  

  INSERT INTO database.table (id, bu, full_action)
  SELECT id, bu, act
  FROM cte
  WHERE rn = 1;
);

我没有要测试的Teradata 系统，所以不是100% 可以按原样工作，但请试一试。您可能需要将RECURSIVE 更改为WITH RECURSIVE 以及CTE 查询的顺序（即将RECURSIVE 放在第一位）。看看这两个链接：

Teradata Forum - Multiple With Clause
teradata Forum - Common Table Expressions