Question

我有以下的sql表结构，我试图使用codeigniter从2个表中获取值。

table: salesman

id    sales_name     ref_id
1       kevin      174
2       mike       574
3       nick       777


table: sales_report

 id   salesman_id   product     purchased_date      dispatched 
 1    2             BF0214      04-November-2011        Yes
 2    2             CF0474      09-November-2011        No
 3    2             BF0111      10-November-2011        No
 4    3             BF0714      15-November-2011        Yes
 5    3             BF0435      15-November-2011        Yes
 6    2             BF0335      18-November-2011        Yes
 7    1             BF0714      22-November-2011        Yes
 8    1             BF0335      25-November-2011        Yes

我将salesman_id传递给模型，以便在我的视图中抓取并显示值。

我的html表格如下

Ref ID   |  Salesman Name  | Last product Sold | Sold Date  | Dispatched Status

我有怎样查询从salesman表中获取sales_name和ref_id并从sales_report表中获取最新产品名称，dispatched和purchase_date的问题？

例如：

   Ref ID   |  Salesman Name  | Last product Sold |   Sold Date         | Dispatched Status
    174            kevin            BF0335            25-November-2011       Yes
    574            mike             BF0335            18-November-2011       Yes
    777            nick             BF0435            15-November-2011       Yes

Answer 1

使用

GROUP BY

ORDER BY

完成这项工作

Answer 2

您需要使用sales_report，SELECT salesman中的LEFT JOIN值来获取sales_name和ref_id，{{3 } purchased_date（DESC首先获取最新的第一个而不是最早的第一个），ORDER BY salesman.id使每个推销员只返回一行。

SELECT * FROM sales_report LEFT JOIN salesman ON sales_report.salesman_id = salesman.id ORDER BY purchased_date DESC GROUP BY salesman.id

Answer 3

你应该通过两个criteras找到最后一个产品：它的销售日期和它的id;因为有些产品可能会在一天内售出。所以，试试这个 -

SELECT s.ref_id, s.sales_name, sr.product, sr.purchased_date, sr.dispatched FROM salesman s
  JOIN (
    SELECT salesman_id, product, purchased_date, dispatched FROM (
      SELECT salesman_id, product, purchased_date, dispatched, IF(@salesman_id = salesman_id, @i := @i + 1, @i := 1) n, @salesman_id := salesman_id
        FROM sales_report, (SELECT @i:= 0, @salesman_id = NULL) vars
      ORDER BY salesman_id ASC, purchased_date DESC, id DESC) t
    WHERE t.n = 1
      ) sr
  ON s.id = sr.salesman_id;

使用php和mysql从表中获取最新值

3 个答案: