Below is the C sharp code to connect with the sql data base in .net

usingSystem.Data.Sql;
usingSystem.Data.SqlClient;

// FUNCTION TO CONNECT TO THE SQL SERVER DATABASE

privatevoidconnectToSQLServer()
        {

// SQL CONNECTION REPRESENTS AN OPEN CONNECTION TO SQL SERVER DATABASE

SqlConnectionsqlConnection = newSqlConnection(connectionString);   

//CONNECTION STRING IS STRING FOR CONNECTING TO THE SQL SERVER
// e.g : "Data Source=servername;Initial Catalog=databasename;Integrated Security=True"

try
            {

    SqlCommandsqlCommand=newSqlCommand("Select * from tableName");// QUERY TO BE EXECUTED
sqlConnection.Open();// OPEN SQL CONNECTION
sqlCommand.Connection=sqlConnection;
    DataTabletableResult = newDataTable();
        tableResult.Load(sqlCommand.ExecuteReader()) ;// RETURN RESULT OF QUERY
            }
catch (Exception ex)
            {
            }
finally
            {

// CLOSE SQL CONNECTION IF IT IS OPEN

if(sqlConnection!=null&&sqlConnection.State==ConnectionState.Open)
sqlConnection.Close();            }
        }