詳解在ASP.NET中用LINQ實現數據處理
一.引用命名空間
System.Data.Linq
System.Data.Linq.Mapping （需要在項目中先引用System.Data.Linq）
二.為數據庫表創建實體類
Table(Name="Employees")] |
常用的屬性聲明，可以很好的描述表中字段的屬性：
Name: 字段的名稱
DbType: 字段的數據類型
IsDbGenerated: 是否自動生成
CanBeNull: 字段是否為空
Storage: 保存數據的類字段名
三.創建一個強類型的數據環境
我們的數據庫系統可能會和多種類型的數據源打交道，所以應該使我們的程序有和數據源進行創建連接的能力。這里我們將創建的NorthwindDb類繼承DataContext基類。DataContext類表示LINQ to SQL 框架的主入口點。
其中有相關的處理LINQ to SQL的類，方法等。
public class NorthwindDb:DataContext |
四.創建Web From
首先為GridView綁定數據
private void BindGridView(string criteria)
{
string strConn = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;
NorthwindDb db = new NorthwindDb(strConn);
IEnumerableresults;
if (criteria == string.Empty)
{
results=db.Employee.ToArray();
}
else
{
results = (from c in db.Employee
where c.FirstName.Contains(criteria)
select c).ToArray();
}
GridView1.DataSource = results;
GridView1.DataBind();
}
搜索按鈕只需將參數傳進去即可BindGridView(TextBox1.Text);
如果選中了GridView中的某一行，則需要將選中的數據綁定到DetailsView 中進行編輯使用。
private void BindDetailsView()
{
int employeeID = (int)GridView1.SelectedValue;
string strConn = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;
NorthwindDb db = new NorthwindDb(strConn);
var results = from emp in db.Employee
where emp.EmployeeID == employeeID
select emp;
DetailsView1.DataSource = results;
DetailsView1.DataBind();
}protected void GridView1_SelectedIndexChanging(object sender, GridViewSelectEventArgs e)
{
GridView1.SelectedIndex = e.NewSelectedIndex;
}
protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
{
int employeeID = (int)GridView1.SelectedValue;
string strConn = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;
BindDetailsView();
}
接下來就是對數據的增刪改操作：
protected void DetailsView1_ItemUpdating(object sender, DetailsViewUpdateEventArgs e)
{
string strConn = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;
NorthwindDb db = new NorthwindDb(strConn);
var results = from emp in db.Employee
where emp.EmployeeID == (int)DetailsView1.SelectedValue
select emp;
results.First().FirstName = ((TextBox)DetailsView1.Rows[1].Cells[1].Controls[0]).Text;
results.First().LastName = ((TextBox)DetailsView1.Rows[2].Cells[1].Controls[0]).Text;
db.SubmitChanges();
BindGridView(string.Empty);
}
protected void DetailsView1_ItemInserting(object sender, DetailsViewInsertEventArgs e)
{
string strConn = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;
NorthwindDb db = new NorthwindDb(strConn);
Employee emp = new Employee();
emp.FirstName = ((TextBox)DetailsView1.Rows[1].Cells[1].Controls[0]).Text;
emp.LastName= ((TextBox)DetailsView1.Rows[2].Cells[1].Controls[0]).Text;
db.Employee.InsertOnSubmit(emp);
db.SubmitChanges();
BindGridView(string.Empty);
}
protected void DetailsView1_ItemDeleting(object sender, DetailsViewDeleteEventArgs e)
{
string strConn = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;
NorthwindDb db = new NorthwindDb(strConn);
var results = db.Employee.Single(emp => emp.EmployeeID==(int)DetailsView1.SelectedValue);
db.Employee.DeleteOnSubmit(results);
db.SubmitChanges();
BindGridView(string.Empty);
}
更新和添加的操作差不多，只是作了些小的改動。
ok，這就是在ASP.NET中利用LINQ對數據的操作。
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