C#操作SQLServer的一个简单封装

 class DBHandler {

     //SqlConnection数据库连接对象
     private SqlConnection localConnection = null;

     //构造函数中初始化连接对象，传入数据库服务名，数据库实例名，用户名和密码
     public DBHandler(string server, string dataBase, string id, string pwd) {
         String connectionString = "Data Source=" + server + ";Initial Catalog=" + dataBase
                                 + ";User ID=" + id + ";Password=" + pwd;
         this.localConnection = new SqlConnection(connectionString);
     }

     //创建对象后调用该方法判断是否能够成功连接
     public int checkValidate(ref string errMsg) {
         try {
             this.localConnection.Open();
         } catch (Exception ex) {
             errMsg = "[Connecting failed]" + ex.Message;
             return -;
         }
         return ;
     }

     //操作数据库前调用
     private void prepareConnect() {
         switch (this.localConnection.State) {
             case ConnectionState.Broken:
                 this.localConnection.Close(); //先正常关闭，释放资源
                 this.localConnection.Open();
                 break;
             case ConnectionState.Closed:
                 this.localConnection.Open();
                 break;
             case ConnectionState.Connecting:
                 break;
             case ConnectionState.Executing:
                 break;
             case ConnectionState.Fetching:
                 break;
             case ConnectionState.Open:
                 break;
             default:
                 break;
         }
     }

     //执行Update语句，返回更新的行数
     public int doUpdate(string sql, ref string errMsg) {
         prepareConnect();
         SqlCommand localCommand = new SqlCommand();
         localCommand.CommandText = sql;
         localCommand.Connection = this.localConnection;
         try {
             return localCommand.ExecuteNonQuery();
         } catch (Exception ex) {
             errMsg = "[update error]" + ex.Message;
             return -;
         }
     }

     //执行Select语句，返回DataTable结果集
     public void doSelect(string sql, ref DataTable dataTable, ref string errMsg) {
         prepareConnect();
         try {
             SqlDataAdapter dataAdapter = new SqlDataAdapter(sql, this.localConnection);
             dataTable.Clear();
             dataAdapter.Fill(dataTable);
         } catch (Exception ex) {
             errMsg = "[select error]" + ex.Message;
         }
     }

 }