我有这个 mysql 表：

+--------------------+---------+-------+
|      date          | query   | count |
|--------------------+---------+-------|
|2012-11-18 09:52:00 | Michael |   1   |
|2012-11-18 10:47:10 |  Tom    |   2   |
|2012-11-17 15:02:12 |  John   |   1   |
|2012-11-17 22:52:10 |  Erik   |   3   |
|2012-11-16 09:42:01 |  Larry  |   1   |
|2012-11-16 07:41:33 |  Kate   |   1   |
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

等等。我可以简单地获取结果并通过以下代码按日期对它们进行排序：

$queries = mysql_query("SELECT * FROM my_tables ORDER BY date DESC LIMIT 20"); 
while($row = mysql_fetch_array($queries)){
    echo "Name ".$row['query']."";
}

但是如何显示按特定日期排序的表中的元素，如下所示：

In 2012-11-18:
Michael
Tom

In 2012-11-17:
John
Erik

In 2012-11-16:
Larry
Kate

等等。谢谢！

这是 PHP 代码：

$query = mysql_query("SELECT date, query FROM table6 ORDER BY date DESC LIMIT 20");
$group_date = null;
while ($row = mysql_fetch_assoc($query)) {
    if ($group_date !== substr($row["date"], 0, 10)) {
        $group_date = substr($row["date"], 0, 10);
        echo "<h1>$group_date</h1>\n";
    }
    echo "${row['query']}<br>\n";
}

Output:

2012-11-18

Tom

Michael

2012-11-17

Erik

John

2012-11-16

Larry

Kate

请注意，虽然此代码按一列对行进行“分组”，但它可以轻松扩展为按多列对行进行分组。留作练习。