ChuckLu - 博客园

2022年9月14日

摘要： https://www.sqlservercentral.com/forums/topic/charindex-is-not-case-sensitive SELECT CHARINDEX('x', 'X') 这个不区分大小写下面这个会区分大小写 SELECT CHARINDEX('x' coll 阅读全文

posted @ 2022-09-14 18:08 ChuckLu 阅读(38) 评论(0) 推荐(0)

What do two question marks together mean in C#?

摘要： What do two question marks together mean in C#? Ran across this line of code: FormsAuth = formsAuth ?? new FormsAuthenticationWrapper(); What do the t 阅读全文

posted @ 2022-09-14 14:29 ChuckLu 阅读(42) 评论(0) 推荐(0)

How to change your Twitter username

摘要： How to change your Twitter username Your username –– also known as your handle –– begins with the “@” symbol, is unique to your account, and appears i 阅读全文

posted @ 2022-09-14 02:44 ChuckLu 阅读(248) 评论(0) 推荐(0)

2022年9月13日

Extend IQueryable<T> Where() as OR instead of AND relationship

摘要： Extend IQueryable<T> Where() as OR instead of AND relationship 回答2 Use PredicateBuilder<T>. It's probably what you want. Dynamically Composing Express 阅读全文

posted @ 2022-09-13 15:23 ChuckLu 阅读(72) 评论(0) 推荐(0)

2022年9月12日

一道微分方程应用题中的“微”妙解答高等数学

摘要：一道微分方程应用题中的“微”妙解答首先，设导弹的位置为 (x,y) ,由简单的物理及几何知识我们可以列出以下微分方程组然后......然后怎么解呢？我们发现这是一个关于、、x、y、t 的三元微分方程组，这是符合实际的，由于、x、y 都分别是 t 的函数，我们只需要分别解出、x、y 关于阅读全文

posted @ 2022-09-12 17:09 ChuckLu 阅读(123) 评论(0) 推荐(0)

2022年9月9日

WPF binding not updating the view

摘要： WPF binding not updating the view 回答1 You need to implement INotifyPropertyChanged in your ViewModel order to notify the View that the property has ch 阅读全文

posted @ 2022-09-09 17:18 ChuckLu 阅读(68) 评论(0) 推荐(0)

2022年9月8日

高等数学第六章定积分及其应用

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posted @ 2022-09-08 23:38 ChuckLu 阅读(0) 评论(0) 推荐(0)

Cannot convert from an IEnumerable<T> to an ICollection<T>

摘要： Cannot convert from an IEnumerable<T> to an ICollection<T> I have defined the following: public ICollection<Item> Items { get; set; } When I run this 阅读全文

posted @ 2022-09-08 15:24 ChuckLu 阅读(78) 评论(0) 推荐(0)

How can I add an item to a IEnumerable<T> collection?

摘要： How can I add an item to a IEnumerable<T> collection? My question as title above. For example IEnumerable<T> items = new T[]{new T("msg")}; items.ToLi 阅读全文

posted @ 2022-09-08 15:20 ChuckLu 阅读(547) 评论(0) 推荐(0)

What are the Navigation Properties in Entity Framework

摘要： What are the Navigation Properties in Entity Framework 回答1 Navigation properties represents related entites to the principal entity. Foreign Keys are 阅读全文

posted @ 2022-09-08 10:27 ChuckLu 阅读(71) 评论(0) 推荐(0)

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