Question

如何在给定的stall_id的LEFT JOIN上找到tenant_id的MAX值？

$sql = "SELECT * FROM stall s 
        LEFT JOIN tenant t 
        ON t.stall_id = s.stall_id
        LEFT JOIN rent r
        ON r.tenant_id = t.tenant_id AND r.rent_status = 1
        WHERE s.stall_id = 1";

Answer 1

你想要这样吗： -

    SELECT * FROM stall s 
    LEFT JOIN tenant t 
    ON t.stall_id = s.stall_id
    LEFT JOIN rent r
    ON r.tenant_id = t.tenant_id AND r.rent_status = 1
    WHERE s.stall_id = 1 ORDER BY r.tenant_id desc LIMIT 1

Answer 2

我认为在这种情况下你不需要使用MAX()，因为rent_status字段看起来是一个布尔值（1或0）。这意味着一个简单的INNER JOIN可以解决问题。

SELECT * FROM `stall` AS s
INNER JOIN rent AS r ON r.stall_id = s.id AND r.rent_status = 1
WHERE s.stall_id = 1

如何在LEFT JOIN上拥有SQL Max？

2 个答案: