C# SqlConnection 常用SQLServer存取

    public DataSet GetDataSet(string sconn, string cmd)    {        try        {            System.Data.DataSet ds = new System.Data.DataSet();            using (SqlConnection sqlConn = new SqlConnection(sconn))            {                sqlConn.Open();                SqlCommand sqlComm = new SqlCommand();                sqlComm.Connection = sqlConn;                sqlComm.CommandTimeout = 3000;                sqlComm.CommandText = cmd;                SqlDataAdapter adapter = new SqlDataAdapter(sqlComm);                        adapter.Fill(ds,"temp");                                    return ds;            }        }        catch (SqlException e)        {             return null;        }    }    public DataTable GetDataTable(string sconn, string cmd)    {        try        {            DataTable dt = new DataTable();            using (SqlConnection sqlConn = new SqlConnection(sconn))            {                sqlConn.Open();                SqlCommand sqlComm = new SqlCommand();                sqlComm.Connection = sqlConn;                sqlComm.CommandTimeout = 3000;                sqlComm.CommandText = cmd;                SqlDataAdapter adapter = new SqlDataAdapter(sqlComm);                adapter.Fill(dt);                return dt;            }        }        catch (SqlException e)        {             return null;        }    }    public string GetScalar(string sconn, string cmd)    {        try        {            object obj;            using (SqlConnection sqlConn = new SqlConnection(sconn))            {                sqlConn.Open();                SqlCommand sqlComm = new SqlCommand();                sqlComm.Connection = sqlConn;                sqlComm.CommandTimeout = 3000;                sqlComm.CommandText = cmd;                obj = sqlComm.ExecuteScalar();                if (obj == null)                    obj = "";                return obj.ToString();            }        }        catch (SqlException e)        {             return "";        }    }