lambda一些查询语句 

<!--得分数据结构-->
1 <Score>
2     <studentid>1</studentid>
3     <courseid>1</courseid>
4     <score>80</score>
5   </Score>
<!--科目数据结构-->
1 <Course>
2     <courseid>1</courseid>
3     <name>攻击力</name>
4   </Course>
<!--学生数据结构-->
1  <Student>
2     <studentid>1</studentid>
3     <name>大娃</name>
4     <sex>男</sex>
5     <age>13</age>
6     <remark>力大无穷</remark>
7   </Student>
 1 //按年龄排序 
 2 public static List<Student> GetStudentsSortByAge()
 3         {
 4             try
 5             {
 6                //return Global.Data_students.OrderBy(stu => stu.age).ToList();
 7                 return  Global.Data_students.OrderByDescending(stu => stu.age).ToList();
 8             }
 9             catch (Exception exp)
10             { }
11             return null;
12         }
 1 //指定年龄区间
 2 public static List<Student> GetStudentsByAgeBetween(int sage,int bage)
 3         {
 4             try
 5             {
 6                 return Global.Data_students.Where(stu => (stu.age >= sage && stu.age < bage)).ToList();
 7             }
 8             catch (Exception exp)
 9             { }
10             return null;
11         }
//姓名模糊查询
public static List<Student> GetStudentsByNameContains(string name)
        {
            try
            { 
                return Global.Data_students.Where(stu =>stu.name.Contains(name)).ToList();
            }
            catch (Exception exp)
            { }
            return null;
        }
//指定性别查询
public static List<Student> GetStudentsBySexIs(string sex)
        {
            try
            {
                return Global.Data_students.Where(stu => stu.sex==sex).ToList();
            }
            catch (Exception exp)
            { }
            return null;
        } 
 1 //多表查询
 2 public static List<Result> GetScores()
 3         {
 4             try
 5             {
 6                 List<Result> lr = new List<WindowsFormsApplication1.Result>();
 7                 foreach (var v in Global.Data_scores.Join(Global.Data_courses, score => score.courseid, course => course.courseid, (score, course) => new
 8                 {
 9                     studentid = score.studentid,
10                     coursename = course.name,
11                     scores = score.score
12                 }).Join(Global.Data_students, score => score.studentid, student => student.studentid, (score, student) => new
13                 {
14                     studentname = student.name,
15                     coursename = score.coursename,
16                     scores = score.scores
17                 }).ToList()
18                 )
19                 {
20                     Result r = new Result();
21                     r.coursename = v.coursename;
22                     r.score = v.scores;
23                     r.studentname = v.studentname;
24                     lr.Add(r);
25                 };
26                 return lr;
27             }
28             catch (Exception exp)
29             { }
30             return null;
31         }

 

posted @ 2017-06-20 14:07  dyfisgod  阅读(536)  评论(0)    收藏  举报