在后台的类里写：

LinQ操作类名 con = new LinQ操作类名();

1、多条件查询：

并且 &&

var list = con.car.Where(r => r.code == "c014" && r.oil == 8.2m);

或者 ||

var list = con.car.Where(r => r.code == "c014" || r.oil == 8.2m);

2、模糊查询

1.模糊

var list = con.car.Where(r => r.name.Contains(""));

2.开头

var list = con.car.Where(r => r.name.StartsWith(""));

3.结尾

var list = con.car.Where(r => r.name.EndsWith(""));

3、统计查询

1.总个数

var count = con.car.Count();

2.最大值

var Max = con.car.Max(r => r.price);

3.最小值

var Min = con.car.Min(r => r.price);

4.平均值

var avg = con.car.Average(r => r.price);

4、分页查询

跳过，获取

int count = 5;

int pagecount = 1;

var list = con.car.Skip(pagecount * count).Take(count);

skip：跳过 take：取出或者显示

5、排序查询

升序

var list = con.car.OrderBy(r => r.price);

降序

var list = con.car.OrderByDescending(r => r.price);

去重：

var aaa = con.car.Select(r => r.oil).Distinct();

6、外键显示

public 类型 要扩展成的字段名{

get{

return this.brand1.brand_name;

}

}

7、组合查询

交集

var list = list1.Intersect(list2).Intersect(list3);

-------------------------------------------------------------

var list1 = con.car.AsQueryable();

var list2 = con.car.AsQueryable();

var list3 = con.car.AsQueryable();

if (TextBox1.Text.Trim().Length > 0)

{

list1 = list1.Where(r => r.name.Contains(TextBox1.Text.Trim()));

}

if (TextBox2.Text.Trim().Length > 0)

{

list2 = list2.Where(r => r.brand1.brand_name.Contains(TextBox2.Text.Trim()));

}

if (TextBox3.Text.Trim().Length > 0)

{

list3 = list3.Where(r => r.oil == Convert.ToDecimal(TextBox3.Text.Trim()));

}

var list = list1.Intersect(list2).Intersect(list3);

Repeater1.DataSource = list;

Repeater1.DataBind();