Question about the TableInfo function in MapBasic

Question

I have a problem I really can't seem to get my head around, MapInfo crashes when I try to run and if statement.

I have pretty much exactly the same code in another sub to check for other things and that works perfectly fine. It crashes on the zlRow = TableInfo("zerolengths",TAB_INFO_NROWS), I've tried this with zlRow = TableInfo(0,TAB_INFO_NROWS) as there will only be one TAB file open when this rool is running. I just don't know why it works for other subs and queries but not this!!

Sub LenSub

nMID = FrontWindow()

nLayers = MapperInfo(nMID, MAPPER_INFO_LAYERS)

sLayer = LayerInfo(nMID, nLayers, LAYER_INFO_NAME)

Dim sDir as String 

sDir = PathToDirectory$(TableInfo(sLayer,TAB_INFO_TABFILE))

    '###Check for blanks

Dim sLen as string

Dialog
    Title "Length"
    Control statictext
        Title "Enter length field"
    Control edittext
        Value sLen
        into sLen
    Control OKButton
    Control CancelButton

if commandinfo (CMD_INFO_DLG_OK) then

Else
End Program
End if

Run Command "select * from " & sLayer & " where " & sLen & " < 1 into zerolengths"

Dim zlRow as smallint

zlRow = TableInfo("zerolengths",TAB_INFO_NROWS)

if zlRow > 0 then
    Export Multipolylines Into sDir & "zerolengths.csv" Type "CSV" 
    Delimiter "," 
Titles

    Dialog
            Title "Zero lengths"
            Control statictext
                Title "Sections with zero lengths exported into zerolengths.csv"
            Control OKButton
Else
End If

End Sub

Thanks, Alan

Answer 1

It seems it is actually crashing on this line

Export Multipolylines Into sDir & "zerolengths.csv" Type "CSV

Does the table Multipolylines exist elsewhere in your code? Did you mean to export the zerolengths table you created instead?

Answer 2

First, try to generate your analysis with mainfo and save your espacework like (.Wor) (if you have to open a table and apply an SQL query, Do it manually). then open this file with mapBASIC. Compile it and correct the errors; Add these in the begin of your code to commands:

Declare Sub Main
Sub Main

=============

Add at the end:

 end Sub/