Question

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我有这个表单，用户输入 startdate ， enddate 结果将发送到PHP文件，该文件生成结果变量，如下所示：
的 PHP

if(isset($_POST['user_selected_dates'])) {
    $invoice_startdate = $_POST['start_date'];
    $invoice_enddate = $_POST['end_date'];
}

然后有这个讨厌的MySQL查询...

SELECT

  s.student_socialnr, s.student_lastname, s.student_firstname,
  cs.city_name,
  c.customer_name,
  scp.cpl_startdate, scp.cpl_enddate, scp.cpl_coursename, scp.cpl_pricevalue,
  SUM(scpe.scpe_days) AS total_days, scp.cpl_pricevalue * SUM(scpe.scpe_days) AS      total_invoice

 FROM studentcourseplan scp
   INNER JOIN students s ON s.student_id = scp.student_id
   INNER JOIN studentcourseplanelements scpe ON scpe.scpe_cpl_id = scp.cpl_id
   INNER JOIN cityselections cs ON cs.city_id = s.student_city_id
   INNER JOIN customers c ON c.customer_id = s.student_customer_id
 WHERE scp.cpl_startdate BETWEEN '$invoice_startdate' AND '$invoice_enddate'

 GROUP BY scp.cpl_id ORDER BY s.student_lastname ASC

将在表格中输出这样的内容（使用PHP mysql_fetch_array）：

+------------------+------------------+-------------------+---------------+---------------+---------------+----------------+----------------+------------+---------------+
| student_socialnr | student_lastname | student_firstname | customer_name | cpl_startdate | cpl_enddate   | cpl_coursename | cpl_pricevalue | total_days | total_invoice |
+------------------+------------------+-------------------+---------------+---------------+---------------+----------------+----------------+------------+---------------+
| 000000-0000      | Doe              | John              | A name        | 2012-06-01    | 2012-06-30    | A coursename   | 620            | 40         | 24800         |
+------------------+------------------+-------------------+---------------+---------------+---------------+----------------+----------------+------------+---------------+
| 000000-0000      | Clerksson        | Lisa              | A name        | 2012-01-05    | 2012-07-30    | A coursename   | 950            | 10         | 9500          |
+------------------+------------------+-------------------+---------------+---------------+---------------+----------------+----------------+------------+---------------+
| 000000-0000      | Derpson          | Derp              | A name        | 2012-04-01    | 2012-04-05    | A coursename   | 620            | 40         | 24800         |
+------------------+------------------+-------------------+---------------+---------------+---------------+----------------+----------------+------------+---------------+

现在我正在寻找能够执行以下操作的功能：

为$invoice_startdate和$invoice_enddate之间的天数创建一个值。

如果此值小，则列total_days中的结果值进行计算：

列price_value * [新值的结果]并将其输出到每一行（但只有当它小于数据库中的值时...）

也许可以在{{1}中完成} -QUERY？

我真的很喜欢一些帮助。这是我第一个使用PHP和MySQL的网站，所以请耐心等待！

谢谢。

Answer 1

我相信您正在考虑使用MySQL IF（）和TO_DAYS（）函数的组合。所以像这样：

SELECT IF( TO_DAYS(DATE_DIFF('$invoice_enddate', '$invoice_startdate')) < total_days, price_value * ... ) as total_invoice

Answer 2

我通过在查询中添加以下代码来解决这个问题：

CASE WHEN SUM(scpe.scpe_days) > DATEDIFF('$invoice_enddate', '$invoice_startdate') THEN
 (scp.cpl_pricevalue * DATEDIFF('$invoice_enddate', '$invoice_startdate')) ELSE SUM(scpe.scpe_days) * scp.cpl_pricevalue
END AS to_invoice

如果php值小于结果，则MySQL查询SUM结果

2 个答案: