Evaluate string on record table, - vb.net

Question

How to evaluate match on the record table with vb I have a code like this
Dim absenperintah As SqlCommand = New SqlCommand("Select * from mytable where kodetp ='109'", cekdata)
absenperintah.CommandType = CommandType.Text
cekdata.Open()
Dim valuex = "500"
Using cekbaca As SqlDataReader =
absenperintah.ExecuteReader(CommandBehavior.CloseConnection)
If cekbaca.Read = True Then
Dim nilxbaca = cekbaca("rumus_k") --> record in the table is 1906650*(3.7/100)
Dim nilmy = valuex + nilxbaca
Dim result = New DataTable().Compute(nilmy, Nothing)
MsgBox(result)
End If
cekbaca.Close()
End Using
cekdata.Close()
I get the result 185,070,546 it should be result =70,564.55
how to get result =70,564.55 from Dim nilHy = valuex + nilxbaca

Answer 1

Your problem is that you are declaring these numbers as strings and they are being calculated accordingly.
What you think you are doing:
500 + 1906650*(3.7/100) = 70,564.55
If you were processing these as numbers, it would perform math and your calculation would work.
However, you have declared these values as strings. Therefore the code is actually running like this:
"500" + "1906650*(3.7/100)" 'String concatenation. Not math.
5001906650*(3.7/100) = 185,070,546
Try this code instead:
Dim absenperintah As SqlCommand = New SqlCommand("Select * from mytable where kodetp ='109'", cekdata)
absenperintah.CommandType = CommandType.Text
cekdata.Open()
Dim valuex = "500"
Using cekbaca As SqlDataReader =
absenperintah.ExecuteReader (CommandBehavior.CloseConnection)
If cekbaca.Read = True Then
Dim nilxbaca = cekbaca("rumus_k") 'record in the table is "1906650*(3.7/100)"
Dim nilmy = valuex & " + " & nilxbaca 'makes "500 + 1906650*(3.7/100)"
'Note: your next line of code, DataTable.Compute() will evaluate a
' (string) formula over several rows.
Dim result = New DataTable().Compute(nilmy, Nothing)
'Based on this code here, you are only processing one row.
'Maybe .Compute() is totally unnecessary here.
'You would be better to say: result = 500 + nilxbaca
' or maybe declare valuex as integer, to help the compiler treat it like a number instead of a string.
' or maybe your original code did apply this formula over several rows.
' ... In that case, my example would fix your Compute() formula.
MsgBox(result)
End If
cekbaca.Close()
End Using
cekdata.Close()