MySQL：連接表中的最大日期小於

Question

我有3個表 - client ， invoice和invoice_item 。 我需要選擇所有客戶，其最后購買日期少於特定日期。 存儲在invoice_item表中的日期購買，分配給發票的項目以及分配給客戶的發票。 這是我試過的

SELECT c.* FROM client c
INNER JOIN (
            SELECT i.client_id as clid, MAX(item.date_created) as mdt
            FROM invoice i
            INNER JOIN invoice_item item on i.id = item.invoice_id
            GROUP BY i.id
            ) joined
ON joined.clid = c.id
WHERE joined.mdt  < date('2017-01-01')

並且

SELECT c.* FROM client c
WHERE c.id IN (
            SELECT DISTINCT i.client_id FROM invoice i
            INNER JOIN invoice_item item on i.id = item.invoice_id
            GROUP BY i.id
            HAVING MAX(item.date_created) < date('2017-01-01')
            )

兩個查詢都返回錯誤的結果，這是我用來檢查正確性的查詢：

SELECT MAX(invoice_item.date_created) FROM invoice_item
INNER JOIN invoice i on invoice_item.invoice_id = i.id 
WHERE client_id = {some id from the previous query};

對於某些客戶，上述查詢返回的日期大於2017-01-01 。

我做錯了什么？ 謝謝。

Answer 1

您可以按子查詢中的發票標識符對數據進行分組，但是應該在子查詢中按client_id對數據進行分組。

SELECT c.* FROM client c
INNER JOIN (
            SELECT i.client_id as clid, MAX(item.date_created) as mdt
            FROM invoice i
            INNER JOIN invoice_item item on i.id = item.invoice_id
            GROUP BY i.client_id
            ) joined
ON joined.clid = c.id
WHERE joined.mdt  < date('2017-01-01')