Has random have a limit? - sql-server

Question

Im working on a program which generating random numbers. I have use random in generating the build number. I just wondering does random will have a limit? heres my code thank you in advance.
Private Sub agenerate_Click(sender As Object, e As EventArgs) Handles agenerate.Click
Dim rand As New Random
abuildnumber.Text = rand.Next
Dim exist As String = String.Empty
exist &= "select * from stocks "
exist &= "where build_number=#build"
Using conn As New SqlConnection("server=WIN10;user=admin;password=12345;database=pc_parts")
Using cmd As New SqlCommand
With cmd
.Connection = conn
.CommandType = CommandType.Text
.CommandText = exist
.Parameters.AddWithValue("#build", abuildnumber.Text)
End With
Try
conn.Open()
Dim reader As SqlDataReader = cmd.ExecuteReader
If reader.HasRows Then
reader.Close()
abuildnumber.Text = rand.Next
End If
abrand.Enabled = True
apart.Enabled = True
aquantity.Enabled = True
aday.Enabled = True
amonth.Enabled = True
ayear.Enabled = True
add.Enabled = True
conn.Close()
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Using
End Using
End Sub

Answer 1

The Random will never "run out" of numbers, if that's what you are asking, but it will generate duplicates. You should probably avoid creating a new Random instance every time though, as that can lead the the numbers being less randomly distributed across all possible values. You should create a single source of random numbers, and draw from that each time, without recreating it. A class-level field would work well for this in your example.
If you are interested on just "random looking" numbers, with an extremely low chance of duplicates, you may want to investigate Guid.
Your code does contain another issue that concern me, mainly that the line abuildnumber.Text = rand.Next shows that you have Option Strict set to Off. This is a very bad practice that you should try your hardest to avoid. It can introduce subtle bugs that can be hard to track down once your code becomes more complicated.
Good job with the Using statement! I'm impressed that you are using it correctly on both the SqlConnection and the SqlCommand, most people miss the latter.

Answer 2

Yes, Random Numbers have limit. because its return INT value so its limits as per Int data type
Parameters
minValue
Type: System.Int32
The inclusive lower bound of the random number returned.
maxValue
Type: System.Int32
The exclusive upper bound of the random number returned. maxValue must be greater than or equal to minValue.
Return Value Type:
System.Int32 A 32-bit signed integer greater than
or equal to minValue and less than maxValue; that is, the range of
return values includes minValue but not maxValue. If minValue equals
maxValue, minValue is returned.
Here is Reference https://msdn.microsoft.com/en-us/library/2dx6wyd4(v=vs.100).aspx