1、多条件查询：

并且 &&

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("AT"));//contains包含

2.开头

var list = con.car.Where(r => r.name.StartsWith("皇冠"));//startswith以什么开头

3.结尾

var list = con.car.Where(r => r.name.EndsWith("版"));//endswith以什么结尾

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;//一页显示多少条

int pagecount = 1;//第几页

var list = con.car.Skip(pagecount * count).Take(count);//skip：跳过多少条。take：取多少条

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

return this.brand1.brand_name;//brand1是外键表名，与主键表列重名，自动加一

7、组合查询

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);

交集

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

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Repeater1.DataSource = list;

Repeater1.DataBind();