C# Linq的简单使用

来源：互联网发布：怎样使用ps软件编辑：程序博客网时间：2024/04/29 02:15

1.student是数据库中的一张表，学号(stu)和姓名(xingming)是表中的两个字段，学号是主键。

在页面的Page_Load事件中通过Linq查询表中的数据：

    protected void Page_Load(object sender, EventArgs e)
    {
        StudentDataClassesDataContext context = new StudentDataClassesDataContext();
        Table<student> list = context.GetTable<student>();
        var query = from student in list select student;
        foreach (var student in query)
        {
            Response.Write(student.xuehao+","+student.xingming+"<br>");
        }
    }

在页面中通过Linq在数据库中添加数据：

    protected void btn_Add_Click(object sender, EventArgs e)
    {
        student stu = new student();
        stu.xuehao = txt_XueHao.Text;
        stu.xingming = txt_XingMing.Text;

        StudentDataClassesDataContext context = new StudentDataClassesDataContext();
        context.student.InsertOnSubmit(stu);
        context.SubmitChanges();
        //重新刷新数据
        Table<student> list = context.GetTable<student>();
        var query = from student in list select student;
        foreach (var student in query)
        {
            Response.Write(student.xuehao + "," + student.xingming + "<br>");
        }
    }

通过Linq修改数据：

    protected void btn_Modify_Click(object sender, EventArgs e)
    {
        StudentDataClassesDataContext context = new StudentDataClassesDataContext();
        var query = from student in context.student where student.xuehao == "001" select student;
        foreach (var student in query)
        {
            student.xingming = "宋学习";
        }
        context.SubmitChanges();
    }

通过Linq删除数据：

    protected void btn_Delete_Click(object sender, EventArgs e)
    {
        StudentDataClassesDataContext context = new StudentDataClassesDataContext();
        var query=from student in context.student where student.xuehao=="001" select student;
        foreach (var student in query)
        {
            context.student.DeleteOnSubmit(student);
        }
        context.SubmitChanges();
    }

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