在JQGrid中动态形成查询

我想从表中动态查询数据，并根据登录的用户显示它。我有两个文件：一个是index.php，它捕获用户的管理产品，如：

$currentUser = CurrentUser::getInstance();
$UserID = $currentUser->getId();
//Get admin products
$que1 = mysql_query("SELECT productid from admin_levels WHERE level>1 AND userid=$UserID ORDER BY productid");
$op1="";
while($row1 = mysql_fetch_row($que1)){
    foreach($row1 as $cell1){
        $op1.=$cell1.",";
    }
}
$temp1=strlen($op1)-1;
$op1=substr($op1,0,$temp1);
//op1 contains admin products for sql command
$_SESSION['w1']=$op1;

op1字符串包含类似的内容：

16,17,20,114,125

现在我想把它添加到我的jqgrid查询中：

//Get admin products
$y1=$_SESSION['w1'];
$opt1="WHERE issues.productid in (".$y1.")";
//Create query
$grid->SelectCommand = 'SELECT CONCAT(issues.type,"0",issues.kbid) as KBID,issues.issuesummary as Summary,products.productname as Product,issue_priorities.description as Priority,date_format(issues.createddate, "%d/%m/%Y") as Reported,date_format(issues.lastupdated, "%d/%m/%Y") as Updated,issue_status.statusdescription as Status,issue_resolutions.resdescription as Resolution,users.logon as Assigned FROM issues
    INNER JOIN issue_priorities ON issue_priorities.VALUE = issues.PRIORITY - 1 
    INNER JOIN issue_resolutions ON issue_resolutions.RESID = issues.RESOLUTION 
    INNER JOIN users ON users.ID = issues.ASSIGNEDUSERID
    INNER JOIN products ON products.PRODUCTID = issues.PRODUCTID
    INNER JOIN issue_status ON issue_status.STATUSID = issues.STATUS'
    .$opt1;

在回显sql命令时，我得到的是：

SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'issues.productid in (16,17,20,114,125) LIMIT 0, 0' at line 6

如何解决这个问题？