Question

假设我们有2个相关的表

Table1:
id item_id(References to Table2:id) rating

Table2:
id title day position

我需要查询一个查询：对于所有Table2项目，检查表1：评级并将其位置（ASC）置于表1：位置，但仅限于特定日期。每一天 - 新的评级。 1,2 ... 1000

Exmpl:
Table1:
id item_id rating
1  1       2
2  2       1555
3  3       280

我们需要得到：

Table2:
 id title day position
 1  test1 1   1
 2  test2 1   3
 3  test3 1   2
 N  ....  2   ...

Answer 1

怎么样？

SELECT  a.*, b.*
FROM    table2 a
        INNER JOIN table1 b
            ON a.id = b.item_id
WHERE   day BETWEEN day_1 AND day_2
ORDER   BY a.position ASC

尝试一下，

UPDATE  table2 e
        INNER JOIN
        (
            SELECT  c.*, 
                    @rank:=@rank+1 row_rank
            FROM
                    (
                        SELECT  a.*, b.*
                        FROM    table2 a
                                INNER JOIN table1 b
                                    ON a.id = b.item_id
                        WHERE   day BETWEEN day_1 AND day_2
                    ) c, (SELECT @rank:=0) d
            ORDER   BY c.rating ASC
        ) f ON e.ID = f.ID
SET     e.position = f.row_rank

需要Mysql复杂的查询帮助

1 个答案: