房租管理小软件(四):对linq的使用
1.对LInq的封装如下:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 private static System.Data.Linq.Mapping.MappingSource mappingSource = new AttributeMappingSource(); 2 public static MyFZDataContext a = null; 3 static String path = Application.StartupPath; 4 public MyFZDataContext(): base(getConnstring(), mappingSource) 5 { 6 7 } 8 9 public MyFZDataContext(bool b): base(getConnstring(), mappingSource) 10 { 11 this.ObjectTrackingEnabled = b; 12 } 13 14 15 public static string connstring = ""; 16 public static XmlSerialize xml = new XmlSerialize(); 17 public static Common.Setting set = xml.DeSerialize(); 18 19 public static string getConnstring() 20 { 21 String Ip = set.IP; 22 string user = set.User; 23 string pass = set.Password; 24 string DB = set.DB; 25 connstring = "Data Source=" + Ip + ";Initial Catalog=" + DB + ";Persist Security Info=True;User ID=" + user + ";Password=" + pass + "" + ";Application Name=" + "NetHotel"; 26 return connstring; 27 } 28 29 public static MyFZDataContext getDataContext() 30 { 31 if (a == null) 32 { 33 34 a = new MyFZDataContext(false); 35 } 36 return a; 37 38 }
2.在代码中使用时加入
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 using System.Data.Linq; 2 using System.Linq; 3 using DataBase;
3.一个从数据库,得到数据的例子
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 MyFZDataContext dataContext = new MyFZDataContext(); 2 var v1 = from t in dataContext.VIEW_LD 3 where 4 t.账号.Contains(textEdit_Search.Text) || 5 t.手机.Contains(textEdit_Search.Text) || 6 t.承租人.Contains(textEdit_Search.Text) 7 select t; 8 DataTable dt = DataFunction.LINQToDataTable(v1); 9 this.gridControl1.DataSource = dt;
4.事务的使用
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #region 增加//增加 2 MyFZDataContext dataContext = new MyFZDataContext(); 3 if (dataContext.Connection != null) { dataContext.Connection.Open(); } 4 System.Data.Common.DbTransaction tran = dataContext.Connection.BeginTransaction(); 5 dataContext.Transaction = tran; 6 try 7 { 8 dataContext.SubmitChanges(); 9 10 tran.Commit(); 11 MessageBox.Show("保存成功"); 12 this.Close(); 13 } 14 catch (Exception ex) 15 { 16 17 tran.Rollback(); 18 MessageBox.Show(ex.Message); 19 } 20 #endregion
5.把得到数据转成dataTable
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 public static DataTable LINQToDataTable<T>(IEnumerable<T> varlist) 2 { 3 DataTable dtReturn = new DataTable(); 4 5 // column names 6 PropertyInfo[] oProps = null; 7 8 if (varlist == null) return dtReturn; 9 10 foreach (T rec in varlist) 11 { 12 //// Use reflection to get property names, to create table, Only first time, others 13 //will follow 14 if (oProps == null) 15 { 16 oProps = ((Type)rec.GetType()).GetProperties(); 17 foreach (PropertyInfo pi in oProps) 18 { 19 Type colType = pi.PropertyType; 20 21 if ((colType.IsGenericType) && (colType.GetGenericTypeDefinition() 22 == typeof(Nullable<>))) 23 { 24 colType = colType.GetGenericArguments()[0]; 25 } 26 27 dtReturn.Columns.Add(new DataColumn(pi.Name, colType)); 28 } 29 } 30 31 DataRow dr = dtReturn.NewRow(); 32 33 foreach (PropertyInfo pi in oProps) 34 { 35 dr[pi.Name] = pi.GetValue(rec, null) == null ? DBNull.Value : pi.GetValue 36 (rec, null); 37 } 38 39 dtReturn.Rows.Add(dr); 40 } 41 return dtReturn; 42 }