group p by p.CategoryID into g表示对p按CategoryID字段归类。其结果命名为g,一旦重新命名,p的作用域就结束了,所以,最后select时,只能select g。 2.最大值 var q = from p in db.Products group p by p.CategoryID into g select new { g.Key, MaxPrice = g.Max(p => p.UnitPrice) }; 语句...
这个示例在Group By子句后使用Where子句查找所有至少有10种产品的类别。 说明:在翻译成SQL语句时,在最外层嵌套了Where条件。 10.多列(Multiple Columns) varcategories = from p in db.Products group p by new { p.CategoryID, p.SupplierID } into g select new { g.Key, g }; 语句描述:Linq使用Group...
说明:先按ZhiFuQuDao进行分类,然后获取每个分类的最高一笔交易金额赋给MaxPrice。最小值、平均值和求和实现和此类似,替换关键之即可3.多列(Multiple Columns)var dateQDList = from T in hisDZD group T by new { T.JiaoYiRQ, T.JiaoYiQDMC } into g select new { g.Key.JiaoYiRQ, g.Key.JiaoYiQ...
方法 Sum 會加入 子句中 select 選取的所有專案值。 您可以呼叫 Min 或Max 方法來取代 Sum,以修改此查詢,以擷取指定目錄樹狀目錄中的最大或最小檔案。 C# 複製 string startFolder = """C:\Program Files\dotnet\sdk"""; // Or // string startFolder = "/usr/local/share/dotnet/sdk";...
C# Linq Group By on multiple columns C# LINQ List<KeyValuePair<string, KeyValuePair<int, int>>> Group by to List<KeyValuePair<string, List<KeyValuePair<int, int>>> C# LINQ one condition, return multiple columns and rows C# LINQ order by not working for a SQL table with a primary ke...
(file).LengthwherefileLen >0selectfileLen;// Cache the results to avoid multiple trips to the file system.long[] fileLengths = fileQuery.ToArray();// Return the size of the largest filelonglargestFile = fileLengths.Max();// Return the total number of bytes in all the files...
If an operator is marked in two columns, two input sequences are involved in the operation, and each sequence is evaluated differently. In these cases, it is always the first sequence in the parameter list that is evaluated in a deferred, streaming manner. Expand table Standard query operato...
elementSelector Func<TSource,TElement> 用來將每個來源項目對應至IGrouping<TKey,TElement>之項目的函式。 resultSelector Func<TKey,IEnumerable<TElement>,TResult> 用來從各個群組建立結果值的函式。 comparer IEqualityComparer<TKey> 用來比較索引鍵的IEqualityComparer<T>。
Example, a database table is know to have duplicate rows of data where the duplicates are by multiple columns in a table which requires a business user to make decisions on which data is valid and which data is not valid along with the possibilities to merge data then delete extra...
GroupJoin Index Intersect IntersectBy Join Last LastOrDefault LongCount Max MaxBy Min MinBy OfType Order OrderBy OrderByDescending OrderDescending Prepend Reverse Select SelectMany SequenceEqual Single SingleOrDefault Skip SkipLast SkipWhile Sum Take ...