PHP如何查询SQL加载变量的表如下图

选择线路
<select name="xianlu">
<option value="0203">203</option>
<option value="0207">207</option>
<option value="0213">213</option>
<option value="0214">214</option>
<option value="0225">225</option>
<option value="0283">283</option>
</select>
选择不同的线路加载不懂得表
原句是这个,
$q="SELECT * FROM `line` LEFT JOIN research2 on line.busname = research2.busname WHERE banben is NULL or banben like '%{$_REQUEST['banben']}%'";
根据原句修改后报错
$q="SELECT * FROM `'%{$_REQUEST['xianlu']}%'` LEFT JOIN research2 on '%{$_REQUEST['xianlu']}%'.busname = research2.busname WHERE banben is NULL or banben like '%{$_REQUEST['banben']}%'";
------解决思路----------------------
$q="SELECT * FROM `{$_REQUEST['xianlu']}` LEFT JOIN research2 on `{$_REQUEST['xianlu']}`.busname = research2.busname WHERE banben is NULL or banben like '%{$_REQUEST['banben']}%'";