ADO.NET中不常用的功能

测试数据：

 

SqlConnection conn = new SqlConnection("Data Source=192.168.6.4;Initial Catalog=chapter30;uid=sa;pwd=123456;");    SqlCommand cmd = new SqlCommand();    string sqlText = @"Select * from Student                        Select * from Class                        Select * from SelectClass                         Select * from Teacher                        ";    SqlDataAdapter adapter = new SqlDataAdapter(cmd);    DataSet ds = new DataSet();     cmd.Connection = conn;    cmd.CommandText = sqlText;     adapter.TableMappings.Add("Table", "Student");    adapter.TableMappings.Add("Table1", "Class");    adapter.TableMappings.Add("Table2", "SelectClass");    adapter.TableMappings.Add("Table3", "Teacher");     try    {        conn.Open();        adapter.Fill(ds);    }    catch    {    }    finally    {        conn.Close();    }     DisplayTableData(ds.Tables["Student"]);    DisplayTableData(ds.Tables["Class"]);    DisplayTableData(ds.Tables["SelectClass"]);    DisplayTableData(ds.Tables["Teacher"]);     var student=ds.Tables["Student"];    var classes=ds.Tables["Class"];    var selectclass=ds.Tables["SelectClass"];var teacher=ds.Tables["Teacher"];

 

 

 

 

DataRow的行状态

    DataRow有4种状态：unchange,modify,detach,deleted

//unchangeDisplayRowState(student.Rows[0]); //unchange //modifystudent.Rows[0][1] = "new_" + student.Rows[0][1].ToString();DisplayRowState(student.Rows[0]); //detachvar tmpRow = student.Rows[0];student.Rows.Remove(tmpRow);DisplayRowState(tmpRow); //deletedstudent.Rows[0].Delete();DisplayRowState(student.Rows[0]); 

 

 

DataRow的数据版本

//数据行的原始值           var tmpRow2=student.Rows[1];tmpRow2[1] = "new" + tmpRow2[1].ToString();Console.WriteLine(tmpRow2[1, DataRowVersion.Default]);Console.WriteLine(tmpRow2[1, DataRowVersion.Current]);Console.WriteLine(tmpRow2[1, DataRowVersion.Original]);            //调用Proposed需要调用beginedit方法tmpRow2.BeginEdit();Console.WriteLine(tmpRow2[1, DataRowVersion.Proposed]);tmpRow2.EndEdit();  通过关系获取数据//一对多ds.Relations.Add("teachers", ds.Tables["Teacher"].Columns["Id"],ds.Tables["Class"].Columns["TeacherId"]);            //多对多的关系在这里会被拆分了1对多ds.Relations.Add("selectclass",    new DataColumn[]{    ds.Tables["Class"].Columns["Id"],    //ds.Tables["Student"].Columns["Id"]    },    new DataColumn[]{    ds.Tables["SelectClass"].Columns["ClassId"],    //ds.Tables["SelectClass"].Columns["StudentId"]    }    ); //var rows = tmpRow3.GetChildRows("students");//var rows = tmpRow3.GetChildRows("teachers");var rows = tmpRow3.GetChildRows("selectclass");foreach (DataRow tmp in rows){    foreach (var tmp2 in tmp.ItemArray)    {        Console.Write("{0}\t", tmp2);    }    Console.WriteLine();}

执行结果

 

 

 

 

数据约束

//设置主键student.PrimaryKey = new DataColumn[] {     student.Columns["Id"]}; //设置外键ForeignKeyConstraint fk = new ForeignKeyConstraint(student.Columns["Id"], selectclass.Columns["StudentId"]);fk.UpdateRule = Rule.Cascade;selectclass.Constraints.Add(fk);  //设置唯一约束UniqueConstraint uq = new UniqueConstraint(student.Columns["Id"]);student.Constraints.Add(uq);

 

 

 

用XSD文件生成ADO.NET对象

//将Schema文件抓换为类对象，命令 XSD [schema文件名] /d /out:输出的文件路径//看来Microsoft把O/R进行到底，连Xml文件都不放过。Books books = new Books();books.book.AddbookRow("MJ传奇一", "P123456789", "王小帅", "清华出版社", "99");books.book.AddbookRow("MJ传奇二", "P123456789", "王小帅", "清华出版社", "99");books.book.AddbookRow("MJ传奇三", "P123456789", "王小帅", "清华出版社", "99");books.book.AddbookRow("MJ传奇四", "P123456789", "王小帅", "清华出版社", "99");books.book.AddbookRow("MJ传奇五", "P123456789", "王小帅", "清华出版社", "99");books.book.AddbookRow("MJ传奇六", "P123456789", "王小帅", "清华出版社", "99"); foreach (Books.bookRow book in books.book){    Console.WriteLine(book.Name);} 

 

执行结果：