带有聚合和 RIGHT JOIN 的 PostgreSQL 查询不过滤

Question

我在一对多地图上有两个 tables，库存和地块，在地块上 table 我有一个名为 deleted 的布尔字段，所以我真的不删除行，但是更改要忽略的标志并且不计入查询，我正在尝试合并一个视图的查询，但是如果我添加已删除的字段，则查询的 RIGHT JOIN 表现得像 INNER JOIN 并且我想要 ALL FROM下面示例中的清单工作正常，但不排除 table jap.lots.

上的任何已删除记录

    CREATE VIEW view_inventory_lots AS 
SELECT count(lots.*) AS lots,
sum(lots.qty_available) AS available,
sum(lots.qty_received) AS received,
sum(lots.qty_on_hand) AS onhand,
sum(lots.qty_allocated) AS allocated,
inventories.* 
FROM jap.lots RIGHT JOIN jap.inventories
 ON jap.lots.inventory_id = jap.inventories.inventory_id
  GROUP BY inventories.inventory_id;

如果我尝试修改此视图以添加 lot.deleted 字段以使用以下查询进行过滤：

SELECT count(lots.*) AS lots,
sum(lots.qty_available) AS available,
sum(lots.qty_received) AS received,
sum(lots.qty_on_hand) AS onhand,
sum(lots.qty_allocated) AS allocated,
lots.deleted,
inventories.* 
FROM jap.lots RIGHT JOIN jap.inventories
 ON jap.lots.inventory_id = jap.inventories.inventory_id
 WHERE lots.deleted = false
  GROUP BY inventories.inventory_id, lots.deleted;

结果只有在批次 table 上有记录的库存行，因此 RIGHT JOIN 的目的被忽略，表现为 INNER JOIN

有什么想法吗？提前致谢

Answer 1

在 where 子句中使用 "outer" table 中的列将外连接转换为内连接。将 table 的条件移动到 join 条件：

FROM jap.lots 
  RIGHT JOIN jap.inventories 
     ON jap.lots.inventory_id = ap.inventories.inventory_id
    AND lots.deleted = false
GROUP BY ...

Answer 2

我发现 left joins 更容易遵循 -- 将所有行保留在 第一个 table 中，匹配行放在其余部分。您的问题是 where 子句中的条件撤消了外部连接。

我会这样写：

SELECT count(l.*) AS lots,
       sum(l.qty_available) AS available,
       sum(l.qty_received) AS received,
       sum(l.qty_on_hand) AS onhand,
       sum(l.qty_allocated) AS allocated,
       l.deleted,
       i.* 
FROM jap.inventories i LEFT JOIN
     jap.lots l LEFT JOIN 
     ON l.inventory_id = i.inventory_id AND
        l.deleted = false
GROUP BY i.inventory_id, l.deleted;

另请注意 table 别名和限定列名的使用。这些使查询更易于编写和阅读。此外，它们使它更加一致：您对 table 名称的使用在整个查询过程中不一致。

带有聚合和 RIGHT JOIN 的 PostgreSQL 查询不过滤

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