LinQ高级查询：
1、模糊查询（包含）
Repeater1.DataSource = con.car.Where(r =>r.name.Contains(s)).ToList();
2、开头
Repeater1.DataSource = con.car.Where(r =>r.name.StartsWith(s)).ToList();
3、结尾
Repeater1.DataSource = con.car.Where(r =>r.name.EndsWith(s)).ToList();
4、个数
IEnumerable<car> clist = con.car; int count =clist.Count;
5、最大最小值平均值
con.car.Max(r => r.price); con.car.Min(r => r.price);
con.car.Average(r => r.price);
6、求和、升序、降序
con.car.Sum(r => r.price); Repeater1.DataSource = con.car.OrderBy(r => r.price); Repeater1.DataSource = con.car.OrderByDescending(r => r.price);
7、分页
集合的Skip方法：跳过多少条数据
Take方法：取前多少条数据
例：打开页面绑定第一页的数据
int count = 4;
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
using (Data0928DataContext con = new Data0928DataContext())
{
Repeater1.DataSource = con.Users.Take(count).ToList();
Repeater1.DataBind();
}
}
}
8、组合查询
首先介绍一下IQueryable集合，在LinQ中使用此集合，不会立马查询出实际的数据，而是在真正使用到此集合时才会去执行查询，可以提高服务器内存的效率，避免占用内存过多导致服务器崩溃，但需注意如果中途把此集合ToList()则会立刻执行并返回实际的数据。
using (Data0928DataContext con = new Data0928DataContext())
{
IQueryable<Users> ulist = con.Users;
if (name.Length > 0)
{
ulist = ulist.Where(r => r.UserName.Contains(name));
}
if (nick.Length > 0)
{
ulist = ulist.Where(r => r.NickName.Contains(nick));
}
if (year.Length > 0)
{
ulist = ulist.Where(r => Convert.ToDateTime(r.Birthday).Year.ToString() == year);
}
Repeater1.DataSource = ulist.Take(count);
Repeater1.DataBind();
}
9、集合的交集
集合的Intersect方法，取两个集合的交集
var allList = nameList.Intersect(brandList);
