假设我有一个包含动态添加内容的 HTML 表格,需要如下所示:
+----+---------------------+---------------------+--------------------------+-----------------------------+
| ID | A | B | C | Elapsed since last checkout |
+----+---------------------+---------------------+--------------------------+-----------------------------+
| 1 | 2018-09-01 00:00:00 | 2018-09-03 00:00:00 | 2 days 0 hours 0 minutes | unknown |
| 2 | 2018-09-05 00:00:00 | 2018-09-06 00:00:00 | 1 days 0 hours 0 minutes | 2 days 0 hours |
| 3 | 2018-09-06 00:00:00 | 2018-09-08 00:00:00 | 2 days 0 hours 0 minutes | 0 days 0 hours |
+----+---------------------+---------------------+--------------------------+-----------------------------+
A 列和 B 列通过表单添加到表中。 C 列和“已用时间...”根据前一行和当前行的值进行计算。
当我尝试将表数据从 Php/MySql 输出到 HTML 中时,这就是我得到的:
+----+---------------------+---------------------+--------------------------+-----------------------------+
| ID | A | B | C | Elapsed since last checkout |
+----+---------------------+---------------------+--------------------------+-----------------------------+
| 2 | 2018-09-05 00:00:00 | 2018-09-06 00:00:00 | 1 days 0 hours 0 minutes | 2 days 0 hours |
| 3 | 2018-09-06 00:00:00 | 2018-09-08 00:00:00 | 2 days 0 hours 0 minutes | 0 days 0 hours |
+----+---------------------+---------------------+--------------------------+-----------------------------+
我正在使用这个问题的逻辑:How to get next/previous record in MySQL?组成我的 SQL 语句以从当前行的上一行中获取值,但不幸的是第一行没有显示:
"SELECT * FROM (select * from bookings WHERE id < $id ORDER BY id DESC LIMIT 1) AS x ORDER BY id LIMIT 1";
如何显示数据库中的所有行并从当前行的上一行中选择一个mysql单元格在一条 SQL 语句中?
如果您需要浏览的话,这是我的完整代码。我正在使用嵌套查询,因为我不知道该怎么做...(我读到 JOIN
和 LEFT JOIN
但根据我的理解,只有当您使用不同的表时,情况并非如此我。)
$sqlQuery = "SELECT * FROM bookings";
$result = mysqli_query($conn, $sqlQuery);
$resultCheck = mysqli_num_rows($result);
if ($resultCheck > 0) {
while ($row = mysqli_fetch_assoc($result)) {
$id = $row['id'];
$out = $row['check_out'];
$in = $row['check_in'];
$sum = $row['sum'];
$sqlQueryLastDate = "SELECT * FROM (select * from bookings WHERE id < $id ORDER BY id DESC LIMIT 1) AS x ORDER BY id LIMIT 1";
$resultLastDate = mysqli_query($conn, $sqlQueryLastDate);
$resultCheckLastDate = mysqli_num_rows($resultLastDate);
if ($resultCheckLastDate > 0) {
while ($rowLastDate = mysqli_fetch_assoc($resultLastDate)) {
$lastInDate = $rowLastDate['check_in'];
//echo "previous row's in date:" .$lastInDate;
$sqlQueryCurrentDate = "SELECT * FROM (select * from bookings WHERE id = $id ORDER BY id DESC LIMIT 1) AS x ORDER BY id LIMIT 1";
$resultCurrentDate = mysqli_query($conn, $sqlQueryCurrentDate);
$resultCheckCurrentDate = mysqli_num_rows($resultCurrentDate);
if ($resultCheckCurrentDate > 0) {
while ($rowCurrentDate = mysqli_fetch_assoc($resultCurrentDate)) {
$currentOutDate = $rowCurrentDate['check_out'];
//echo "current row's out date:" .$currentOutDate;
$lastIn = new DateTime($lastInDate);
$currentOut = new DateTime($currentOutDate);
$intervalLastCurrent = $lastIn->diff($currentOut);
$elapsedLastCurrent = $intervalLastCurrent->format('%a days %h hours');
echo "
<tr>
<td>".$id."</td>
<td>".$out."</td>
<td>".$in."</td>
<td>".$sum."</td>
<td>".$elapsedLastCurrent."</td>
</tr>
";
} /*$sqlQueryCurrentDate*/
}
} /*$sqlQueryLastDate*/
}
} /*$sqlQuery*/
}
?>
即使您能为我提供必要的术语来使其发挥作用,我也会做自己的研究。例如,有人建议我使用 LEFT JOIN
但经过研究后发现它并不适合我想要实现的目标。
我尝试实现但无法实现的事情:
How can I subtract a previous row in sql?
SQL Previous row from the same column
(还有更多)
最佳答案
解决这个问题的正确方法是使用仅在 MySQL 8 中可用的窗口函数
如果没有窗口函数,您可以使用类似以下查询的内容:
SELECT
*,
(SELECT value FROM bookings WHERE id < b.id ORDER BY id LIMIT 1) AS prev
FROM
bookings b
ORDER BY id;
关于php - 如何在一个 SQL 语句中从当前行的前一行获取 "use"mysql 单元格,并显示包括第一行在内的所有行?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/52243512/