Question

使用Postgres 9.6，我将一行（选定列）从一个表复制到另一个表。我正在跑步：

INSERT INTO copy_on_write(id, images)
    SELECT id, images
    FROM listings
    WHERE id = 1 AND posted_by = foo
ON CONFLICT (id) DO UPDATE SET images = listings.images

因为ID已经存在而发生冲突，我收到了missing FROM-clause entry for table "listings"。

所以，我试过了：

INSERT INTO copy_on_write(id, images)
    SELECT id, images
    FROM listings
    WHERE id = 1 AND posted_by = foo
ON CONFLICT (id) DO UPDATE SET images = images FROM listings

然后我得到syntax error at or near "FROM"

如何处理此ON CONFLICT (id)，以便在行ID已存在时更新images列？

Answer 1

使用excluded：

INSERT INTO copy_on_write(id, images) 
SELECT id, images 
FROM listings 
WHERE id = 1 AND posted_by = 'foo' 
ON CONFLICT (id) DO UPDATE SET images = excluded.images;

来自the documentation:

conflict_action

（...）ON CONFLICT DO UPDATE中的SET和WHERE子句可以使用表的名称（或别名）访问现有行，并使用特殊excluded表访问建议插入的行。

在ON CONFLICT中将行列从一个表复制到另一个表

1 个答案: