LINQ怎么根据“某个字段”去除重复数据查询

Distinct方法的第二重载可以

Enumerable.Distinct<TSource> (IEnumerable<TSource>, IEqualityComparer<TSource>)，

例如数据类为

class School

{

public int Id { getset}

public string Name { getset}

//是否重点学校

public bool IsKeySchool { getset}

}

实现IEqualityComparer<School>的比较器类为

class SchoolComparer : EqualityComparer<School>

{

public override bool Equals(School x, School y)

{

return x.IsKeySchool==y.IsKeySchool

}

public override int GetHashCode(School obj)

{

return obj.IsKeySchool.GetHashCode()

}

}

原始列表为

var schoolList = new List<School>{

new School{Id=1, Name="三中",IsKeySchool=true},

new School{Id=2, Name="五中",IsKeySchool=true},

new School{Id=3, Name="十中",IsKeySchool=false},

new School{Id=4, Name="十五中",IsKeySchool=true},

new School{Id=5, Name="二十中",IsKeySchool=false},

}

执行

var tempList = schoolList.Distinct(new SchoolComparer())

结果就只有两条“三中”和“十中”

text类型就别做DISTINCT了，效率会让你吐血。

实在想做的话，尝试newslist = newslist.OrderBy(x=>x.nID).ToList().Distinct()

将数据加载入内存，用CLR来做DISTINCT

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