Redshift SQL 用 GROUP 逗号分隔字段

Posted 2023-03-30

【中文标题】Redshift SQL 用 GROUP 逗号分隔字段

【英文标题】：Redshift SQL to comma separate a field with GROUP

【发布时间】：2019-12-10 09:59:53

【问题描述】：

我想用逗号分隔 Redshift 中的字段值和 GROUP BY 其他两个字段。

样本数据：

table_schema table_name column_name 
G1           G2         a
G1           G2         b
G1           G2         c
G1           G2         d
G3           G4         x
G3           G4         y
G3           G4         z

预期输出：

table_schema table_name column_name 
G1           G2         a, b, c, d
G3           G4         x, y, z

我可以在 MSSQL 中这样做：

SELECT table_schema, table_name, column_name = 
    STUFF((SELECT ', ' + column_name
           FROM your_table b 
           WHERE b.table_schema = a.table_schema AND b.table_name = a.table_name
          FOR XML PATH('')), 1, 2, '')
FROM information_schema.tables t
INNER JOIN information_schema.columns c on c.table_name = t.table_name AND c.table_schema = t.table_schema
GROUP BY table_schema, table_name

在 PostgreSQL 中，这将是：

SELECT table_schema, table_name, String_agg(column_name, ',')
FROM information_schema.tables t
INNER JOIN information_schema.columns c on c.table_name = t.table_name AND c.table_schema = t.table_schema
GROUP BY table_schema, table_name

但 Redshift 不包含 STRING_AGG 函数。

我不知道如何在 Redshift 中执行此操作。

编辑

Using the answer from here does NOT WORK:

SELECT CUST_ID,
       LISTAGG("ORDER", ', ')
WITHIN GROUP (ORDER BY "ORDER")
OVER (PARTITION BY CUST_ID) AS CUST_ID
FROM Table
ORDER BY CUST_ID

我的版本：

SELECT t.table_name, LISTAGG("column_name", ', ')
WITHIN GROUP (ORDER BY "column_name")
OVER (PARTITION BY t.table_name) AS table_schema
FROM information_schema.columns t
ORDER BY t.table_name

它给了我以下错误：

0A000：Redshift 表不支持指定的类型或函数（每条 INFO 消息一个）。

我不明白，因为我只从单个节点中选择？

【参考方案1】：

SELECT t.CUST_ID, c.orders
FROM Table t JOIN
      (SELECT cust_id, LISTAGG("ORDER"::text, ', ')
WITHIN GROUP (ORDER BY "ORDER") as orders
       FROM table t
       GROUP BY cust_id
      ) c
      ON t.cust_id = c.cust_id
ORDER BY CUST_ID;