SQL Insert Query Using C#

Question

I\'m having an issue at the moment which I am trying to fix. I just tried to access a database and insert some values with the help of C#

The things I tried (worked)

Answer 1

public static string textDataSource = "Data Source=localhost;Initial 
Catalog=TEST_C;User ID=sa;Password=P@ssw0rd";
public static bool ExtSql(string sql) {
    SqlConnection cnn;
    SqlCommand cmd;
    cnn = new SqlConnection(textDataSource);
    cmd = new SqlCommand(sql, cnn);
    try {
        cnn.Open();
        cmd.ExecuteNonQuery();
        cnn.Close();
        return true;
    }
    catch (Exception) {
        return false;
    }
    finally {
        cmd.Dispose();
        cnn = null;
        cmd = null; 
    }
}