Check if a record exists in the database

Question

I am using these lines of code to check if the record exists or not.

SqlCommand check_User_Name = new SqlCommand(\"SELECT * FROM Table WHERE ([user] = \'\" +         


        

Answer 1

I was asking myself the same question, and I found no clear answers, so I created a simple test.

I tried to add 100 rows with duplicate primary keys and measured the time needed to process it. I am using SQL Server 2014 Developer and Entity Framework 6.1.3 with a custom repository.

Dim newE As New Employee With {.Name = "e"}
For index = 1 To 100
  Dim e = employees.Select(Function(item) item.Name = "e").FirstOrDefault()
  If e Is Nothing Then
    employees.Insert(newE)
  End If
Next  

2.1 seconds

Dim newE As New Employee With {.Name = "e"}
For index = 1 To 100
  Try
    employees.Insert(newE)
  Catch ex As Exception
  End Try
Next  

3.1 seconds