嗨，伙计们，我正在努力改进我的查询以获得更好的性能，是否有可能以更好的方式编写此查询，非常感谢您的帮助
$query = " SELECT A FROM out_org where zone_id='1'";
$query2 = " SELECT A FROM out_dis where zone_id='1'";
$result = mysql_query($query);
$result2 = mysql_query($query2);
echo "<table border=1 style='background-color:#F0F8FF;' >";
echo "<caption><EM>my table</EM></caption>";
echo "<tr>";
echo "<th>" .OA. "</th>" ;
echo "<th>" .DA. "</th>";
echo "<th>" .total. "</th>";
echo "</tr>";
while($row = mysql_fetch_array($result) )
{
while( $row2 = mysql_fetch_array($result2)){
echo "<tr>";
echo "<td>" .$row['A']."</td>";
echo "<td>" .$row2['A']."</td>";
echo "<td>" .$total = $row['A'] - $row2['A']."</td>";
echo "</tr>";
}
echo "</table>";
}
使用连接将 SQL 更改为一个查询，并在查询中执行减法：
$query = "SELECT (o1.A - o2.A) as value
FROM out_org o1
LEFT JOIN out_dis o2
ON o1.zone_id = o2.zone_id
WHERE o1.zone_id='1'";