Build String Using Escape Sequences

Roll over me

using Escape sequences. I have tried but i am getting error

this way i have tried.

DataSet dsTool = new DataSet();

string strToolTip = o.ToString();

string strCn = "Server=server;Database=pubs;User Id=uid;Password=pwd";

SqlConnection cn = new SqlConnection(strCn);

SqlCommand cm = new SqlCommand("select testname,testtext from testtabs where testid=" + strToolTip, cn);

SqlDataAdapter dap = new SqlDataAdapter();

if (dsTool.Tables[0].Rows.Count > 0)

strReturn = new StringBuilder("");

strReturn = @" # \" onmouseover=\""showToolTip(event,'" + dsTool.Tables[0].Rows[0]["testtext"].ToString() + "');return false\">"+o.ToString()+"";