You need to be very careful while doing this sort of thing - any little errors are going to break it, and can be hard to track down. A few I've spotted are: You have the 'scope' parameter out of sequence when building the data to sign. Data must be ordered alphabetically by key for the oauth signature to be correct. You use "GET" as a parameter for calculateBaseString although you're using POST You miss out the & delimiter when adding the oauth_signature You call curl_setopt($ch, CURLOPT_POSTFIELDS twice, overwriting the OAuth signed data with a single parameter. It's very possible there are other errors I've not spotted. Niall

As already pointed out, use parameters: SqlParameter[^]. But if you still for some reason want to use literals in SQL statements, add apostrophes when you're adding texts to the statement: chk1 = "select Sno from Student where SID = '"+ @smemno.Text.ToString() + "'"; The need to optimize rises from a bad design.My articles[^]