sql server .. pdf format

For storing the file, you can use varbinary(max) type in sql table. Then first you read file into a memory stream:

FileStream st = new FileStream(@"C:\pdfname.pdf", FileMode.Open);
            byte[] buffer = new byte[st.Length];
            st.Read(buffer, 0, (int)st.Length);
            st.Close();

then put that stream into byte array, and then insert the byte array to sql:

SqlConnection conn = new SqlConnection("...");
            SqlCommand cmd = new SqlCommand("UPDATE SomeTable SET pdf=@pdf WHERE ID = 1", conn);
            cmd.Parameters.AddWithValue("@pdf", buffer);
            conn.Open();
            int i = cmd.ExecuteNonQuery();
            conn.Close();

If you want to "remember" the file names, you should open up another column in the table for storing file names. For retrieving files, just do the reverse:

SqlConnection connection = new SqlConnection ("...");
        connection.Open ();
        SqlCommand command = new 
          SqlCommand ("select pdf from Table", connection);
        byte[] buffer = (byte[]) command.ExecuteScalar ();
        connection.Close();
        FileStream fs = new FileStream(@"C:\test.pdf", FileMode.Create);
        fs.Write(buffer, 0, buffer.Length);
        fs.Close();

If your file is too big to handle with integers, you should implement buffer mechanism;i.e. save bytes in manageable portions.
Examples for this and further information can be found here