php mysql删除不了中文

Question

<?phpinclude('houtaipost.php');include('hosst.php');$xxboo = $_POST['xbook'];$tpos = new poi();if( $tpos -> post($xxboo) ){die('书名不能为空');}$xsel = "SELECT * FROM txt201807 WHERE txtname=$xxboo";$qwe = $sql -> query( $xsel );$sx = $qwe->fetch_array();if ( $sx == NULL ) {die("没有此书或书名错误");};$del = "DELETE FROM txt201807 WHERE txtname=$xxboo";$sql -> query( $del );header("location: houtai.html");?>前文件已加入utf8的相关代码如果中文前面有数字，只需输入数字也能删除，例如“12书啊啊”，只需输入“12”也能删除“12书啊啊”，很奇怪