I have written some code for retrieving 3 seperate columns from my database, yet for some reason it isn't loading all of the records which result from my query.
Or well, at least it doesn't seem to do so.
Also, for some reason it won't show me a messagebox which should tell me howmany records have been read after the reader is closed.
Here's my code:
Public Class frmPlayerLocations
Dim str(2), loc As String
Dim xx, yy As Integer
Dim itm As ListViewItem
Private Sub frmPlayerLocations_Load(sender As Object, e As EventArgs) Handles MyBase.Load
ListView1.Columns.Add("ID", 60, HorizontalAlignment.Left)
ListView1.Columns.Add("Name", 115, HorizontalAlignment.Left)
ListView1.Columns.Add("Approximate Location", 115, HorizontalAlignment.Left)
Dim qry = "SELECT profile.unique_id, profile.name, survivor.worldspace FROM profile, survivor WHERE survivor.unique_id = profile.unique_id AND survivor.is_dead = '0' ORDER BY profile.name"
Dim connection As MySqlConnection
connection = New MySqlConnection()
connection.ConnectionString = "Host=" & adminPanel.IP & ";port=" & adminPanel.port & ";user=" & adminPanel.username & ";password=" & adminPanel.password & ";database=" & adminPanel.DBname & ";"
connection.Open()
Dim cmd As New MySqlCommand(qry, connection)
Dim reader As MySqlDataReader = cmd.ExecuteReader()
Dim count As Integer = 0
While reader.Read()
count += 1
str(0) = reader.GetString(0)
str(1) = reader.GetString(1)
loc = reader.GetString(2)
loc = Mid(loc, loc.IndexOf(",") + 3)
xx = CInt(Replace(Mid(loc, 1, loc.IndexOf(",")), ".", ",", 1, -1, CompareMethod.Text))
xx = (xx / 10000)
loc = Mid(loc, loc.IndexOf(",") + 2)
yy = CInt(Replace(Mid(loc, 1, loc.IndexOf(",")), ".", ",", 1, -1, CompareMethod.Text))
yy = 152 - (yy / 10000)
If xx < 100 Then
If xx < 10 Then
loc = "00" & xx.ToString & " | "
Else
loc = "0" & xx.ToString & " | "
End If
Else : loc = xx.ToString & " | "
End If
If yy < 100 Then
If yy < 10 Then
loc &= "00" & yy.ToString
Else
loc &= "0" & yy.ToString
End If
Else : loc &= yy.ToString
End If
str(2) = loc
itm = New ListViewItem(str)
ListView1.Items.Add(itm)
End While
reader.Close()
connection.Close()
MessageBox.Show(count)
End Sub
End Class
Edit: I noticed that when calling the form twice in a row, the second time I do get this error:
An unhandled exception of type 'System.ArgumentException' occurred in Microsoft.VisualBasic.dll Additional information: Argument 'Length' must be greater or equal to zero.
And it refers to this line of code:
yy = CInt(Replace(Mid(loc, 1, loc.IndexOf(",")), ".", ",", 1, -1, CompareMethod.Text))
Last but not least, the values which are used in that line of code:
loc "7.305e-04]]" String
yy 131 Integer
PS: This may be helpful: the values which are in survivor.worldspace are in this format initially:
[168,[1291.16,5343.54,0.27]]
If the message box is not being displayed then the most likely situation is that an exception is being thrown inside the while loop which is probably silently caught somewhere else.
Unfortunately there are just too many places where an exception might occur withing that while loop so it's hard to say from just looking at that code. It could be trying to cast a DBNull to string, or an index out of bounds, etc.
My suggestion is to either step through with the debugger and identify the offending line, or put a try catch inside the while loop and put a break-point inside the catch. That should give you information about what (and where) the exception is occurring is..
Based on your update it looks like the problem is the arguments passed to the Mid() functions. Based on your data it looks like you are attempting to get a sub-string of loc using the start index of 1 and the end index of -1 which is what loc.IndexOf(",") returns in that case because there is no , (comma) in loc.
You probably want to re-factor that code a bit.. In particular it looks like you are actually trying to replace . with , but doing it after your attempt to call Mid(). That seems to be your problem!