nedash says:
cmd.Parameters.AddWithValue(
"@Description"
,CKdes.Text.Replace(
"src="
+
'"'
, "src=
" + '"
' + testurl))
Replace above code with below.
cmd.Parameters.AddWithValue("@Description", CKdes.Text.Replace("src=" + '"', "src=" + '"' + "http://mysite.com"));