ADO.NET常用对象详解之:DataSet对象
DataSet中的几个重要对象:
TablesCollection对象:DataSet 里的表用DataTable来表示,一个DataSet里面可以包含多个DataTable,这些DataTable就构成了 TablesCollection对象。每个DataTable中都包含一个ColumnsColleciton和一个RowsCollection对 象。
RelationsCollection对象:各个DataTable之间的关系通过DataRelation来表达,这些DataRelation构成的集合就是RelationsCollection对象。
ExtendedProperties对象:这个对象用来定义特定的信息,比如密码、更新时间等。
1.DataTable对象
创建一个DataTable:
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创建表列
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创建表达式列
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2.DataView对象
DataView就时数据视图,为数据库结构提供了外模式的实现。同时DataView也可以为窗体控件和Web控件提供数据绑定功能,在每一个DataTable中内建了一个DataView为:DataTable.DefaultView()。
创建DataView:
DataView sortedView=new DataView(dataTable);
对DataView进行排序:
dataTable.DefaultView.sort="lastName";
dataTable.DefaultView.sort="lastName,FirstName DESC";
对DataView进行筛选和排序:
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3.DataColumn对象
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4.DataRow对象
调用NewRow方法来创建一个新的DataRow对象
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对行进行批处理更改:
BeginEdit()开始更改,EndEdit()结束更改,同时将更改结果写入DataSet,CancelEdit(),取消更改
例如:
row.BeginEdit();
对row进行更改
row.EndEdit();
从DataTable中删除DataRow对象:
一:DataRowCollection对象的Remove方法
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二:DataRow对象的Delete方法
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比较:Remove方法时从DataRowCollection中删除DataRow,而Dalete方法只是对删除的行做标记。
DataRow类包括RowState属性。RowState属性值表示从第一次创建DataTable(或从数据库加载DataTable)开始,行是 否发生更改,如何更改以及通过何种方式更改。属性的可选值:Modified | Detached | Added。
5.创建表关系
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6.绑定数据
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