Question

我需要创建一个teradata宏，以便首先将信息提取到易失性表中，然后执行CTE从该易失性表中提取数据并将其插入到teradata表中，尝试了各种方法都失败了，谢谢帮助！

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，您可以切换到一次定义的全局临时表，然后只需将其插入/选择即可，而不用创建CREATE VOLATILE TABLE。

但是在您的情况下，不需要临时表以及效率低下的递归处理即可获得“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

将给您类似的结果。

Answer 2

要继续我的评论，您应该能够在同一条语句中定义多个CTE。使RECURSIVE CTE起作用可能很棘手，但这听起来似乎是可行的。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;
);

我没有一个Teradata系统可以测试，因此不是100％可以按原样工作，但是请尝试一下。您可能需要将RECURSIVE更改为WITH RECURSIVE，还需要将CTE查询的顺序更改（即，将RECURSIVE放在第一位）。看一下这两个链接：

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

Teradata宏具有易失性表和CTE，可将数据插入表

2 个答案: