/*********************Any/All/Contains/Concat/Union/Intersect/Except/take/skip/SqlMethods操作练习**********************************/
//判断没有成绩的学生
var list = from s in
ctx.T_Student
where
!s.T_Score.Any()
select s;
//判断有成绩大于80的学生
var list1 = (from s in
ctx.T_Student
where s.T_Score.Any(t => t.score >
80)
select
s).Distinct();
//所有科目成绩大于80的学生
var list2 = from s in
ctx.T_Student
where
s.T_Score.All(t=>t.score>80)
select s;
//查询黄阳是否参加过考试
string[] names = {
"黄阳"};
var
list4 = from s in
ctx.T_Score
where
names.Contains(s.T_Student.stuName)
select s;
//查询黄阳是否参加过考试
var list3 = from s in
ctx.T_Score
where (new string[] { "黄阳"
}).Contains(s.T_Student.stuName)
select s;
//参加过考试但是不是黄阳的同学
var list5 = from s in
ctx.T_Score
where !(new string[] { "黄阳"
}).Contains(s.T_Student.stuName)
select s;
//contains也可以包含一个对象，如查询那些学生参加了课程编号为001的第一个同学，对于contains只能包含一个实体，不能保护实体集
var temp1 = (from s in
ctx.T_Score
where s.stuNumber ==
"001"
select
s).First();
var result =
ctx.T_Student.Where(p=>p.T_Score.Contains(temp1));
//查找黄阳和黄波的所有成绩
string[] names1 =
{"黄阳","黄波"};
var result2 =
ctx.T_Score.Where(f=>names1.Contains(f.T_Student.stuName));
//或者也可以这样
var result3 = from s in
ctx.T_Score
where (new string[] { "黄阳", "黄波"
}).Contains(s.T_Student.stuName)
select s;
//对于concat，连接不同的集合，不会自动过滤相同项,而且它只能对于单列进行连接，对多列进行连接，会报语法错误，因为没有相应的扩展方法
var result4 = (from s in
ctx.T_Student
select
s.stuName)
.Concat(from k in
ctx.T_Score
select k.T_Cource.courceName
);
//合并所有的学生
var result5 = ((from s in
ctx.T_Student
select
s.stuNumber)
.Union
(from k in
ctx.T_Score
select
k.stuNumber)).Distinct();
//交集
var
result6 = (from s in
ctx.T_Student
select
s.stuNumber).Intersect
(from k in
ctx.T_Score
select
k.stuNumber);
//差集
var
result7 = (from s in
ctx.T_Student
select
s.stuNumber).Intersect
(from k in
ctx.T_Score
select
k.stuNumber);
//查询前三个学生的信息
var result8 = (from s in
ctx.T_Student
select
s).Take(3);
//查询三个学生以外的所有学生信息
var result9 = (from s in
ctx.T_Student
select
s).Skip(3);
//当学号为2091723时候，就停止获取学生信息
var result10 = (from s in
ctx.T_Student
select s).TakeWhile(k => k.stuNumber ==
"2091723");
//当学号为2091723时候，就停止跳过学生信息，并获取后边的所有学生信息
var result11 = (from s in
ctx.T_Student
select s).SkipWhile(k => k.stuNumber ==
"2091723");
//可以用skip和take来对数据进行分页，这非常方便
//查看姓名以黄开头的学生信息,这时候程序需要引入using
System.Data.Linq.SqlClient;命名空间
var result12 = from s in
ctx.T_Student
where
SqlMethods.Like(s.stuName,"黄%")
select s;
//查询学号为2X917X2的学生
var result13 = from s in
ctx.T_Student
where SqlMethods.Like(s.stuNumber,
"2_917_2")
select s;
//比较时间的操作分别有：DateDiffDay、DateDiffHour、DateDiffMillisecond、DateDiffMinute、DateDiffMonth、DateDiffSecond、DateDiffYear
，也是sqlMethods方法，而数据库中的表并没有设计时间的字段，所以就不演示了
//SQL语句进行编辑重新查询,需要引用命名空间using
System.Data.Linq;
var fn =
CompiledQuery.Compile(
(DB_StudentDataContext ctx1,string
stuName)=>
from s in
ctx1.T_Student
where
s.stuName==stuName
select
s
);
var
data1 =
fn(ctx,"黄阳");
var data2 = fn(ctx,"黄波");
Linq无聊练习系列6--Any/All/Contains/Concat/Union/Intersect/Except/take/skip/SqlMethods操作练习,布布扣,bubuko.com
Linq无聊练习系列6--Any/All/Contains/Concat/Union/Intersect/Except/take/skip/SqlMethods操作练习