在插入数据之前检查具有条件的特定列的SUM

I need help! I just want to insert data from user but before that it will check first if the 'dami' column in database is <=100, if yes then it will insert the data entered by the user if no then it will prompt the user.

But with my code it keeps inserting regardless of the 'dami' sum. Badly need it! Here's my code!

public function do_create_businesscard($txttelno,$txttelno1,$txtfaxno,$txtmobileno,$txtmobileno1,$txtemail,$txtemail1,$txtPieces,$is_deleted)
    {
        $sql = "SELECT (SELECT SUM(dami)
                FROM tbl_business_card_information
                WHERE is_deleted = 1)
                AS 'Total'";

        if ('Total' >= 100){
        echo "Sorry but you already reach you maximum request";

        }else{

        $sql = "INSERT INTO tbl_business_card_information (`tel_no`,`tel_no1`,`fax_no`,`mobile_no`,`mobile_no1`,`email`,`email1`,`dami`) VALUES (?,?,?,?,?,?,?,?)";

        $data = array($txttelno,$txttelno1,$txtfaxno,$txtmobileno,$txtmobileno1,$txtemail,$txtemail1,$txtPieces);                           
        $query = $this->db->query($sql,$data);
        return $query;  
        }
    }

Thank You !

Your usage of SELECT is wrong. Here is the way.

public function do_create_businesscard($txttelno,$txttelno1,$txtfaxno,$txtmobileno,$txtmobileno1,$txtemail,$txtemail1,$txtPieces,$is_deleted)
{
    $sql = "SELECT SUM(dami) FROM tbl_business_card_information WHERE is_deleted = 1";
    $result = $this->db->query($sql);
    $row = $result->fetch_array(MYSQLI_NUM);
    $total = $row[0];
    if ($total > 100){
        echo "Sorry but you already reach you maximum request";
    }else{
        $sql = "INSERT INTO tbl_business_card_information (`tel_no`,`tel_no1`,`fax_no`,`mobile_no`,`mobile_no1`,`email`,`email1`,`dami`) VALUES (?,?,?,?,?,?,?,?)";

        $data = array($txttelno,$txttelno1,$txtfaxno,$txtmobileno,$txtmobileno1,$txtemail,$txtemail1,$txtPieces);                           
        $query = $this->db->query($sql,$data);
        return $query;  
    }
}