C# linq中的简单选择查询

假设我有一个学生表，我想显示ID为1的学生

SELECT *
FROM STUDENT ST
WHERE ST.ID = 1

这就是我在林克如何做到的

StudentQuery = from r in oStudentDataTable.AsEnumerable()
                                     where (r.Field<int>("ID") == 1)
                                     select r;
            oStudentDataTable = StudentQuery.CopyToDataTable();

如何在Linq中实现这一点？

尝试IEnumerable。包含：

使用

也可以尝试以下方法：

var list = new List<int> { 1, 2, 3, 4, 5 };

List<StudentQuery> result = (from r in oStudentDataTable.AsEnumerable()
              where (list.Contains(r.Field<int>("ID"))
              select new StudentQuery
              { /*
                .Your entity here
                .
                */
              }).ToList<StudentQuery>();

---

如果列表变得更长，我自己更喜欢哈希集。该列表将由LINQ转换为SQL，转换成in子句，然后由数据库优化。我不认为哈希集会更快。请您为此提供一些帮助：

var list = new List<int>(){1,2,3,4,5};
StudentQuery = from r in oStudentDataTable.AsEnumerable()
                                 where (list.Contains(r.Field<int>("ID")))
                                 select r;
        oStudentDataTable = StudentQuery.CopyToDataTable();

var list = new List<int> { 1, 2, 3, 4, 5 };

var result = (from r in oStudentDataTable.AsEnumerable()
              where (list.Contains(r.Field<int>("ID"))
              select r).ToList();

var list = new List<int> { 1, 2, 3, 4, 5 };

List<StudentQuery> result = (from r in oStudentDataTable.AsEnumerable()
              where (list.Contains(r.Field<int>("ID"))
              select new StudentQuery
              { /*
                .Your entity here
                .
                */
              }).ToList<StudentQuery>();