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How to get the last inserted row number?

Apr 6 2021 5:43 PM
This question may seem very very easy (Select COUNT(Id), but in my case is different. I developed a web application with 15 to 25 concurrent users. every time they open the program, I am checking the last row inserted into the database and in C# I created a serial number based on the last row inserted + 1. So say for example below entry:
 
User1 opens up the program:
      DB count = 1
      C# Series = Ser-00001 (displayed in UI)
      User1 inserts a row. success
 
User2 opens up the program:
      DB count = 2
      C# Series = Ser-00002 (displayed in UI)
      User2 inserts a row. success
 
User3 opens up the program:
      DB count = 3
      C# Series = Ser-00003 (displayed in UI)
      User3 inserts a row. success
 
No issue right? But, there will be a time that 2 or more users will open the program at the same time. Now, below is the scenario
 
 
User7 opens up the program:
      DB count = 4
      C# Series = Ser-00004 (displayed in UI)
      User7 inserts a row. success
 
User8 opens up the program:
      DB count = 4
      C# Series = Ser-00004 (displayed in UI)
      User8 inserts a row. failed
 
User9 opens up the program:
      DB count = 4
      C# Series = Ser-00004 (displayed in UI)
      User9 inserts a row. failed
 
This time a big problem suddenly occur! 
 
Now my question is, how do you do it to avoid this type of duplication? Thank you in advance for any posible solution.
          
 

Answers (5)