MapInfo / Mapbasic: simple compile of table from six source tables

Question

I have a project which I am reviving after a gap of some years. It involves several hundred runs within MapInfo, scripted in MapBasic.

I am stuck at a point that is so simple, it's driving me nuts.

At one point within each run, I have six tables, each of a single cell.

These tables are called:

minBNGy maxBNGx minBNGy maxBNGy medBNGx medBNGy

They are min, max and median British National Grid coordinates. Each table is mappable, with a single point.

In each case, the table's single variable has the same name as the table.

Each is a long integer, but for some (probably deliberate) reason I no longer understand, I created these as floats.

I need to compile from these six tables a single table, with the six named cells and their values on a single row. It does not need to be mappable.

I was using this:

Add Column TARGET_TABLE (NEW_VARIABLE)From SOURCE_TABLE 
   Set To SOURCE_VARIABLE 
   Where COL1 = COL1

... but it no longer seems to work.

In my old code, the 'map' was dropped later.

I am using MapInfo / MapBasic v.6.5 on Windows 7 Ultimate 64-bit.

I would be very grateful for any guidance.

Bruce

Answer 1

The solution was derived with assistance from Peter Horsbøll Møller:

' ================================================

'   CALCULATE MIN AND MAX X COORDINATES OF CLUSTER

Open Table Spy60_O as Spy60 Interactive

Dim fMinX As Float
Select * from Spy60 order by caseNo into xSorted
Browse * From xSorted
Fetch First From xSorted
fMinX = xSorted.BNGx
Close Table xSorted 

Dim fMaxX As Float
Select * from Spy60 order by caseNo Desc into xReverseSorted
Browse * From xReverseSorted
Fetch First From xReverseSorted
fMaxX = xReverseSorted.BNGx
Close Table xReverseSorted 

'   CALCULATE MIN AND MAX Y COORDINATES OF CLUSTER

Dim fMinY As Float
Select * from Spy60 order by caseNo into ySorted
Browse * From ySorted
Fetch First From ySorted
fMinY = ySorted.BNGy
Close Table ySorted 


Dim fMaxY As Float
Select * from Spy60 order by caseNo Desc into yReverseSorted
Browse * From yReverseSorted
Fetch First From yReverseSorted
fMaxY = yReverseSorted.BNGy
Close Table yReverseSorted 


' ================================================
'
'   CALCULATE MEDIAN CENTRE X AND Y COORDINATES OF CLUSTER
'
'from: http://testdrive.mapinfo.com/TECHSUPP/MIPROD.NSF/59d125f456480edb852562b5004f2c33/daeed8326071ce0c85256b89005a72ad?OpenDocument
'
' ================================================
'

Browse * From Spy60
dim MedianTableX as string, ColNameX as string, nX as integer
MedianTableX="exTable"
ColNameX="exColumn"
Select BNGx from Spy60 Order By BNGx Into MedianTempX NoSelect
nX=TableInfo(MedianTempX, 8)
Select Avg(BNGx)from MedianTempX where RowID=int((nX+1)/2) or RowID=int((nX+2-(nX mod 2))/2) into MedianFinalX NoSelect
Browse * from MedianFinalX
Commit Table MedianFinalX As medBNGx_O
Open Table medBNGx_O as medBNGx Interactive

Dim fMedX As Float
fMedX  = medBNGx._COL1


Browse * From Spy60
dim MedianTableY as string, ColNameY as string, nY as integer
MedianTableY="exTable"
ColNameY="exColumn"
Select BNGy from Spy60 Order By BNGy Into MedianTempY NoSelect
nY=TableInfo(MedianTempY, 8)
Select Avg(BNGy)from MedianTempY where RowID=int((nY+1)/2) or RowID=int((nY+2-(nY mod 2))/2) into MedianFinalY NoSelect
Browse * from MedianFinalY
Commit Table MedianFinalY As medBNGy_O
Open Table medBNGy_O as medBNGy Interactive

Dim fMedY As Float
fMedY  = medBNGy._COL1