Incorrect syntax near ',' while using update query

[loco]

Following is my code.I have used class in my website.But i am getting error as "Incorrect syntax near ',' ".....can anyone tell me what is wrong in the code..\[code\]protected void btnadd_Click(object sender, EventArgs e) { s1 = "Update tckt_tbl Set class='" + ddlclass.Text + "',dist=" + lbldist.Text + ",no_of_adults=" + ddladults.Text + ",no_of_senior=" + ddlsenior.Text + ",n1='" + txtn1.Text + "',"; s1 += "n2='" + txtn2.Text + "',n3='" + txtn3.Text + "',n4='" + txtn4.Text + "',n5='" + txtn5.Text + "',n6='" + txtn6.Text + "',"; s1 += "ag1=" + txtag1.Text + ",ag2=" + txtag2.Text + ",ag3=" + txtag3.Text + ",ag4=" + txtag4.Text + ",ag5=" + txtag5.Text + ",ag6=" + txtag6.Text + ","; s1 += "gen1='" + txtgen1.Text + "',gen2='" + txtgen2.Text + "',gen3='" + txtgen3.Text + "',gen4='" + txtgen4.Text + "',gen5='" + txtgen5.Text + "',gen6='" + txtgen6.Text + "',"; s1 += "cn1='" + txtchn1.Text + "',cn2='" + txtchn2.Text + "',cag1=" + txtcag1.Text + ",cag2=" + txtcag2.Text + ",cgen1='" + txtcgen1.Text + "',cgen2='" + txtcgen2.Text + "' Where userid=" + Session["suser"].ToString() + ""; con.ExecQuery(s1); Response.Redirect("tcktbook_itckt.aspx"); }\[/code\]