在DAL方法中重用SqlConnection

public class DataAccessLayer
{
    private static SqlConnection _connection;

    public DataAccessLayer()
    {
        if (_connection == null)
        {
            _connection = new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString);
            _connection.Open();
        }
    }

    public DataTable GetData(string sqlQuery)
    {
        using (SqlCommand command = new SqlCommand(sqlQuery, _connection))
        {
            using (SqlDataReader reader = command.ExecuteReader())
            {
                DataTable dataTable = new DataTable();
                dataTable.Load(reader);
                return dataTable;
            }
        }
    }

    public void Dispose()
    {
        if (_connection != null)
        {
            _connection.Close();
            _connection.Dispose();
            _connection = null;
        }
    }
}