Question

tbl_marketing

db_maid db_date     db_customer
1       01-04-2017  xxxx
2       05-04-2017  lll
3       08-04-2017  ggg

tbl_phonecall

db_id  db_mid db_due      db_nextdate  db_pnote
1       2     15-04-2017  16-04-2017   cccc
2       2     17-04-2017  18-04-2017   bbb
3       1     04-05-2017  16-05-2017   ghghh

这是我的查询

选择

  select
 marketing.*,
 phonecall.db_id,
 max(phonecall.db_due) db_due,
 max(phonecall.db_nextdate) db_nextdate,
 phonecall.db_pnote
 from tbl_marketing marketing
 left outer join tbl_phonecall phonecall
 on
 phonecall.db_mid=marketing.db_maid
 group by marketing.db_maid

我想要的结果是来自tbl_marketing的所有行，即使tbl_phonecall中存在Null值 BUT NO DUPLICATE RECORDS ，而tbl_phoencall的最后一行也是db_pnote ，db_due通过tbl_marketing的db_due以tbl_phonecall顺序关联到行

我的查询没有给出我想要的确切结果

输出就像那样

# Date        Customer dueDate    NextDate     pNote
2  05-04-2017 lll      17-04-2017  18-04-2017  bbbb
1  01-04-2017 xxxx     04-05-2017 16-05-2017   ccc
3  08-04-2017 ggg                              ghghh

Answer 1

您可以使用以下内容：

 select  marketing.*,
         phonecall.db_id,
         phonecall.db_due,
         phonecall.db_nextdate,
         phonecall.db_pnote
 from tbl_marketing marketing
 left outer join tbl_phonecall phonecall on phonecall.db_mid=marketing.db_maid
     and phonecall.db_due=(select max(t2.db_due) from tbl_phonecall t2
                            where t2.db_mid=marketing.db_maid)
     and phonecall.db_nextdate=(select max(t3.db_nextdate) from tbl_phonecall t3
                            where t3.db_mid=marketing.db_maid)

Answer 2

您是否希望获得电话中最新日期的所有活动？

SELECT 
    m.*

    ,p.db_id
    ,p.db_due
    ,p.db_nextdate
    ,p.db_pnote

FROM tbl_marketing m

    LEFT JOIN
    (SELECT
            db_id
            ,max(Date) LDate
        FROM tbl_phonecall
        GROUP BY db_id
    ) LastDate
    ON LastDate.db_mid = m.db_maid

        LEFT JOIN tbl_phonecall p
        ON m.db_mid = m.db_maid
        AND LastDate.LDate = p.Date

Mysql从左表中没有重复值的左连接，其中包含最后一个值

2 个答案: