Nettet7. jul. 2024 · 前天在做批量数据导入新增时，要对数据进行有效性判断，其中还要去除重复，如果没出现linq的话可能会新声明一个临时对象集合，然后遍历原始数据判断把符合条件的数据添加到临时集合中，这在有了linq之后显得比较麻烦。 一、首先创建一个控制台应用程序，添加一个Person对象 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 … Nettet在 LINQ 中，GroupBy 运算符用于根据键的指定值对列表/集合项进行分组，并返回 IGrouping 的集合。 LINQ 中的 GroupBy 方法与 SQL group by 语句相同 …
クエリ結果のグループ化 (C# での LINQ) Microsoft Learn
NettetAdd a comment. 2. An alternative way to do this could be select distinct PersonId and group join with persons: var result = from id in persons.Select (x => x.PersonId).Distinct () join p2 in persons on id equals p2.PersonId into gr // apply group join here select new { PersonId = id, Cars = gr.Select (x => x.Car).ToList (), }; Nettetvar results = persons.GroupBy( p => p.PersonId, p => p.car, (key, g) => new { PersonId = key, Cars = g.ToList() }); Basically the contents of the group (when viewed as an … gaming platforms popular in 2006
C# Linq 交集、并集、差集、去重 - 每天进步多一点 - 博客园
Nettet15. jan. 2024 · .NET[C#]使用LINQ从List集合中删除重复对象元素(去重)的方法有哪些？ 问题描述. 比如有如下的List集合： 1 Item1 IT00001 $100 2 Item2 IT00002 $200 3 Item3 IT00003 $150 1 Item1 IT00001 $100 3 Item3 IT00003 $150 Nettet7. apr. 2024 · First scenario is to group people collection by forename. Lambda expression 1 var groups = people.GroupBy(x => x.Forename); Query expression 1 2 var groups = from p in people group p by p.Forename; Both Lambda and Query expression generates the same results which can be displayed with foreach loops. The following example shows how to group source elements by using a single property of the element as the group key. In this case the key is a string, the student's last name. It is also possible to use a substring for the key; see the next example. The grouping operation uses the default equality comparer for the type. Se mer The following example shows how to group source elements by using something other than a property of the object for the group key. In this example, the key is the first letter … Se mer The following example shows how to group source elements by using a Boolean comparison expression. In this example, the Boolean expression tests whether a student's average … Se mer The following example shows how to group source elements by using a numeric range as a group key. The query then projects the results into an anonymous type that contains only the first and last name and the … Se mer The following example shows how to use an anonymous type to encapsulate a key that contains multiple values. In this example, the first key … Se mer gaming plateformes