Select max value in MS Access database - vb.net

Question

I need to select the max value in my row column. When I hit line
(FindCurrentTimeCard = Val(myreader("Row"))
I get an error:
System.IndexOutOfRangeException
Code:
Public Function FindCurrentTimeCard() As Integer
Dim myconnection As OleDbConnection = New OleDbConnection
Dim query As String = "Select MAX(Row) from Table2"
Dim dbsource As String =("Provider=Microsoft.ACE.OLEDB.12.0;DataSource=S:\Docs\PRODUCTION\Shop Manager\Shop_Manager\Shop_Manager\Database2.accdb;")
Dim conn = New OleDbConnection(dbsource)
Dim cmd As New OleDbCommand(query, conn)
Try
conn.Open()
Dim myreader As OleDbDataReader = cmd.ExecuteReader()
myreader.Read()
FindCurrentTimeCard = Val(myreader("Row"))
conn.Close()
Catch ex As OleDbException
MessageBox.Show("Error Pull Data from Table2")
FindCurrentTimeCard = 1
End Try
End Function
Table2

Answer 1

The issue is that when you evaluate an aggregate function (or indeed, any expression performing some operation on a field or fields), the result of such evaluation will be assigned an alias (such as Expr1000) unless an alias is otherwise stated.
Hence, when you evaluate the SQL statement:
select max(table2.row) from table2
MS Access will return the result assigned to an alias such as Expr1000:
Hence, the SQL statement does not output a column named Row, causing your code to fail when attempting to retrieve the value of such column:
FindCurrentTimeCard = Val(myreader("Row"))
Instead, you should specify an alias to which you may refer in your code, e.g.:
select max(table2.row) as maxofrow from table2
With your function then returning the value associated with such column:
FindCurrentTimeCard = Val(myreader("maxofrow"))

Answer 2

Comments and explanations in-line
Public Function FindCurrentTimeCard() As Integer
Dim CurrentTimeCard As Integer
'The Using block ensures that your database objects are closed and disposed
'even it there is an error
'Pass the connection string directly to the connection constructor
Using myconnection As New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;DataSource=S:\Docs\PRODUCTION\Shop Manager\Shop_Manager\Shop_Manager\Database2.accdb;")
Dim query As String = "Select MAX(Row) from Table2"
Using cmd As New OleDbCommand(query, myconnection)
Try
myconnection.Open()
'since you are only retrieving a single value
'you can used .ExecuteScalar which gets the value
'in the first row, first column
CurrentTimeCard = CInt(cmd.ExecuteScalar)
Catch ex As OleDbException
MessageBox.Show("Error Pull Data from Table2")
End Try
End Using
End Using
'vb.net uses the Return statement to return the value of the function
Return CurrentTimeCard
End Function