اشتراک‌ها
دلایل ارتقاء به SQL Server 2017

Following is a chart that shows licensing cost comparison between standard and Enterprise Edition of SQL Server 2012, 2016 and 2017.

Version Edition License Cost 2 Quad core
Processors
4 Quad core
Processors
    Per Core 8 Cores 16 Cores
SQL Server 2012 Standard $1,793 $14,344 $28,688
SQL Server 2012 Enterprise $6,874 $54,992 $109,984
SQL Server 2016\ 2017 Standard $1,858 $14,864 $29,728
SQL Server 2016 \2017 Enterprise $7,128 $57,024 $114,048
دلایل ارتقاء به SQL Server 2017
اشتراک‌ها
کتاب رایگان Java Succinctly Part 2

In this second e-book on Java, Christopher Rose takes readers through some of the more advanced features of the language. Java Succinctly Part 2explores powerful and practical features of Java, such as multithreading, building GUI applications, and 2-D graphics and game programming. Then learn techniques for using these mechanisms in coherent projects by building a calculator app and a simple game with the author.

Table of Contents
  1. Packages and Assert
  2. Reading and Writing to Files
  3. Polymorphism
  4. Anonymous Classes
  5. Multithreading
  6. Introduction to GUI Programming
  7. GUI Windows Builder
  8. 2-D Game Programming 
کتاب رایگان Java Succinctly Part 2
اشتراک‌ها
معرفی 3 ویژگی جدید در C# 8.0

C# is rapidly approaching its third decade of life. Originally released in 2000, the language has grown and changed across 7 major versions. Once a knock off of Java in all but name has jumped out ahead on many aspects. 

معرفی 3 ویژگی جدید در C# 8.0
اشتراک‌ها
معرفی سایت
سایت فوق،یک سایت آموزشی می‌باشد، و در مورد موضوعاتی همچون JAVA،HTML،CSS،CSharp،VB.Net،WPF،Oracle ،PHP ،SQL Serverو بسیاری از زبانهای دیگر، دارای مطالب آموزشی است.
نکته جالب توجه سایت فوق در این است که، مطالبش بصورت خوبی دسته بندی شده است، و مثالهای آن برای یادگیری مفاهیم مختصر و مفید است.
چنانچه برای مشاهده سایت با مشکل مواجه شدید،می بایست از فیلتر شکن استفاده نمایید.
معرفی سایت
اشتراک‌ها
روش های مقایسه اشیاء با null

Check

Code 

Description

Is Null
if(variable is null) return true;

  • 🙂 This syntax supports static analysis such that later code will know whether variable is null or not.
  • 🙁 Doesn’t produce a warning even when comparing against a non-nullable value type making the code to check pointless.
  • 😐 Requires C# 7.0 because it leverages type pattern matching.
Is Not Null
if(variable is { }) return false

  • 🙂 This syntax supports static analysis such that later code will know whether variable is null or not.
  • 😐 Requires C# 8.0 since this is the method for checking for not null using property pattern matching.
Is Not Null
if(variable is object) return false

  • 🙂 Triggers a warning when comparing a non-nullable value type which could never be null
  • 🙂 This syntax works with C# 8.0’s static analysis so later code will know that variable has been checked for null.
  • Checks if the value not null by testing whether it is of type object.  (Relies on the fact that null values are not of type object.)
Is Null
if(variable == null) return true

  • 🙂 The only way to check for null prior to C# 7.0.
  • 🙁 However, because the equality operator can be overridden, this has the (remote) possibility of failing or introducing a performance issue.
Is Not Null
if(variable != null) return false

  • 🙂 The only way to check for not null prior to C# 7.0.
  • 😐 Since the not-equal operator can be overridden, this has the (remote) possibility of failing or introducing a performance issue. 
روش های مقایسه اشیاء با null