phpmyadmin-php调用mysqli查询出错

语句直接在命令行运行就能查出接过来，在phpMyAdmin里面也能查到，但是写到程序里就出错，请大神帮忙看看。


代码是这个

 $sql =" select * from $table_list where $length_left qq $length_right $textif $t;"; $mysqli = new mysqli("localhost","root","root",'qq_db');$mysqli->set_charset("utf8");if ($mysqli->connect_errno){  die("Connect Error :".$mysqli->connect_error);  }$result = $mysqli->query($sql);var_dump($result);$mysqli->close();sql语句实际

运行后就提示bool(false)