分组方法 (LINQ to Entities)

  • 项目

LINQ to Entities 支持多数 LINQ 分组方法，但由于比较器不能转换为数据源，因此不支持接受 IEqualityComparer 的那些方法。有关更多信息，请参见 LINQ to Entities 查询中的标准查询运算符。下表列出了支持的和不支持的分组方法。

支持的和不支持的方法

方法 支持 Visual Basic 函数签名 C# 方法签名

GroupBy

支持

 
Function GroupBy(Of TSource, TKey) ( _
source As IQueryable(Of TSource), _
keySelector As Expression(Of Func(Of TSource, TKey)) _
) As IQueryable(Of IGrouping(Of TKey, TSource))
 
IQueryable<IGrouping<TKey, TSource>> GroupBy<TSource, TKey>(
this IQueryable<TSource> source,
Expression<Func<TSource, TKey>> keySelector
)

GroupBy

不支持

 
Function GroupBy(Of TSource, TKey) ( _
source As IQueryable(Of TSource), _
keySelector As Expression(Of Func(Of TSource, TKey)), _
comparer As IEqualityComparer(Of TKey) _
) As IQueryable(Of IGrouping(Of TKey, TSource))
 
IQueryable<IGrouping<TKey, TSource>> GroupBy<TSource, TKey>(
this IQueryable<TSource> source,
Expression<Func<TSource, TKey>> keySelector,
IEqualityComparer<TKey> comparer
)

GroupBy

支持

 
Function GroupBy(Of TSource, TKey, TElement) ( _
source As IQueryable(Of TSource), _
keySelector As Expression(Of Func(Of TSource, TKey)), _
elementSelector As Expression(Of Func(Of TSource, TElement)) _
) As IQueryable(Of IGrouping(Of TKey, TElement))
 
IQueryable<IGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(
this IQueryable<TSource> source,
Expression<Func<TSource, TKey>> keySelector,
Expression<Func<TSource, TElement>> elementSelector
)

GroupBy

支持

 
Function GroupBy(Of TSource, TKey, TResult) ( _
source As IQueryable(Of TSource), _
keySelector As Expression(Of Func(Of TSource, TKey)), _
resultSelector As Expression(Of Func(Of TKey, IEnumerable(Of TSource), TResult)) _
) As IQueryable(Of TResult)
 
IQueryable<TResult> GroupBy<TSource, TKey, TResult>(
this IQueryable<TSource> source,
Expression<Func<TSource, TKey>> keySelector,
Expression<Func<TKey, IEnumerable<TSource>, TResult>> resultSelector
)

GroupBy

不支持

 
Function GroupBy(Of TSource, TKey, TElement) ( _
source As IQueryable(Of TSource), _
keySelector As Expression(Of Func(Of TSource, TKey)), _
elementSelector As Expression(Of Func(Of TSource, TElement)), _
comparer As IEqualityComparer(Of TKey) _
) As IQueryable(Of IGrouping(Of TKey, TElement))
 
IQueryable<IGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(
this IQueryable<TSource> source,
Expression<Func<TSource, TKey>> keySelector,
Expression<Func<TSource, TElement>> elementSelector,
IEqualityComparer<TKey> comparer

GroupBy

支持

 
Function GroupBy(Of TSource, TKey, TElement, TResult) ( _
source As IQueryable(Of TSource), _
keySelector As Expression(Of Func(Of TSource, TKey)), _
elementSelector As Expression(Of Func(Of TSource, TElement)), _
resultSelector As Expression(Of Func(Of TKey, IEnumerable(Of TElement), TResult)) _
) As IQueryable(Of TResult)
 
IQueryable<TResult> GroupBy<TSource, TKey, TElement, TResult>(
this IQueryable<TSource> source,
Expression<Func<TSource, TKey>> keySelector,
Expression<Func<TSource, TElement>> elementSelector,
Expression<Func<TKey, IEnumerable<TElement>, TResult>> resultSelector
)

GroupBy

不支持

 
Function GroupBy(Of TSource, TKey, TResult) ( _
source As IQueryable(Of TSource), _
keySelector As Expression(Of Func(Of TSource, TKey)), _
resultSelector As Expression(Of Func(Of TKey, IEnumerable(Of TSource), TResult)), _
comparer As IEqualityComparer(Of TKey) _
) As IQueryable(Of TResult)
 
IQueryable<TResult> GroupBy<TSource, TKey, TResult>(
this IQueryable<TSource> source,
Expression<Func<TSource, TKey>> keySelector,
Expression<Func<TKey, IEnumerable<TSource>, TResult>> resultSelector,
IEqualityComparer<TKey> comparer
)

GroupBy

不支持

 
Function GroupBy(Of TSource, TKey, TElement, TResult) ( _
source As IQueryable(Of TSource), _
keySelector As Expression(Of Func(Of TSource, TKey)), _
elementSelector As Expression(Of Func(Of TSource, TElement)), _
resultSelector As Expression(Of Func(Of TKey, IEnumerable(Of TElement), TResult)), _
comparer As IEqualityComparer(Of TKey) _
) As IQueryable(Of TResult)
 
IQueryable<TResult> GroupBy<TSource, TKey, TElement, TResult>(
this IQueryable<TSource> source,
Expression<Func<TSource, TKey>> keySelector,
Expression<Func<TSource, TElement>> elementSelector,
Expression<Func<TKey, IEnumerable<TElement>, TResult>> resultSelector,
IEqualityComparer<TKey> comparer
)

另请参见

概念

支持的和不支持的方法 (LINQ to Entities)