Question

我有3个mysql语句，每个语句给出不同的结果集，我想表示从按时间戳desc排序的查询中收集的所有结果。

例如：如果购买的订单在产品之前有时间戳，则购买订单中的商品应该在产品之前我该怎么做并发送了3个结果集的组合排序结果。我非常感谢任何帮助。谢谢你。

$query=mysql_query("select * from products order by timestamp desc ;");
$numrows = mysql_num_rows($query);
if ($numrows!=0)
{
    $rows = array();
    while($r = mysql_fetch_assoc($query)) {
        $rows[] = $r;
    }
}
echo json_encode($rows);

$query2=mysql_query("select * from user_purchased order by timestamp desc ;");
$numrows2 = mysql_num_rows($query2);
if ($numrows2!=0)
{
    $rows2 = array();
    while($r2 = mysql_fetch_assoc($query2)) {
        $rows2[] = $2r;
    }
}
echo json_encode($rows2);

$query3=mysql_query("select * from delivery order by timestamp desc ;");
$numrows3 = mysql_num_rows($query3);
if ($numrows3!=0)
{
    $rows3 = array();
    while($r3 = mysql_fetch_assoc($query3)) {
        $rows3[] = $r3;
    }
}
echo json_encode($rows3);

Answer 1

要合并所有数据并按日期降序对它们进行排序，您将使用带有UNION ALL的子查询并合并来自所有3个表的未排序结果...然后按时间戳降序排序记录。以下是一个例子。但是，如果它们都具有不同的字段名称且字段名称的数量不同，则可以创建虚拟字段名称以创建一致的信息。它在下面的编辑中描述。

为简单起见，我们假设所有表都具有以下结构

+-------+-----------+------+-----+-------------------+-------+
| Field | Type      | Null | Key | Default           | Extra |
+-------+-----------+------+-----+-------------------+-------+
| id    | int(11)   | YES  |     | NULL              |       |
| ts    | timestamp | NO   |     | CURRENT_TIMESTAMP |       |
+-------+-----------+------+-----+-------------------+-------+

让我们看看每张表中的虚拟数据。

<强>产品

mysql> select * from products;
+------+---------------------+
| id   | ts                  |
+------+---------------------+
|    1 | 2014-03-26 04:39:06 |
|    4 | 2014-03-26 04:40:05 |
+------+---------------------+

<强> User_Purchased

mysql> select * from user_purchased;
+------+---------------------+
| id   | ts                  |
+------+---------------------+
|    2 | 2014-03-26 04:39:19 |
|    5 | 2014-03-26 04:40:00 |
+------+---------------------+

投放

mysql> select * from delivery; +------+---------------------+ | id | ts | +------+---------------------+ | 3 | 2014-03-26 04:39:28 | | 6 | 2014-03-26 04:39:38 | +------+---------------------+

<强> PHP

<?php $db = mysqli_connect('host','usr','pwd'); mysqli_select_db($db,'yourdb'); $data = mysqli_query($db, " select * from ( select 'products' as tbl, id, ts from products union all select 'purchased' as tbl, id, ts from user_purchased union all select 'delivered' as tbl, id, ts from delivery ) a order by ts desc " ); echo "tablename\tid\ttime\n"; foreach ($data as $row) { echo "{$row['tbl']}\t{$row['id']}\t{$row['ts']}\n"; } ?>

<强>输出

tablename id time products 4 2014-03-26 04:40:05 purchased 5 2014-03-26 04:40:00 delivered 6 2014-03-26 04:39:38 delivered 3 2014-03-26 04:39:28 purchased 2 2014-03-26 04:39:19 products 1 2014-03-26 04:39:06

修改

我们说产品表有字段id，productname，productnumber。购买了id，productid，purchaseate。交货有id，purchaseid，deliverydate。

您可以通过执行类似的操作来组合每个查询中的所有字段，然后对mytimestamp进行排序：

select 'products' as tbl, pdt_id, productname as pdt_productname, productnumber as pdt_productnumber, '-' as pur_id, '-' as pur_productid, '-' as pur_purchasedate, '-' as del_id, '-' as del_purchaseid, '-' as del_deliverydate, ts as mytimestamp from products union all select 'purchased' as tbl, '-' as pdt_id, '-' as pdt_productname, '-' as pdt_productnumber, id as pur_id, productid as pur_productid, purchasedate as pur_purchasedate, '-' as del_id, '-' as del_purchaseid, '-' as del_deliverydate, ts as mytimestamp from purchased union all select 'delivered' as tbl, '-' as pdt_id, '-' as pdt_productname, '-' as pdt_productnumber, '-' as pur_id, '-' as pur_productid, '-' as pur_purchasedate, id as del_id, purchaseid as del_purchaseid, deliverydate as del_deliverydate, ts as mytimestamp from delivered

组合3个select语句并按时间戳排序

1 个答案: