Re: MI-L MBX - Add Column statement - MI crashes in a heap!

[Robert Crossley]

Hi,

The trick I use is to make the selection before you add the column, thus 
it only works on the selected records.

Make a selection using SQL of the joined tables and update that. ie.

Select _RowID, MyID, DestinationField, SourceField
        From Table_A, Table_B Where Where _RowID = MyID
        Into UpdateList
Add Column UpdateList(DestinationField)
        From UpdateList
        Set To SourceField
R

On Tue, 11 Nov 2003 17:57:34 +1100, Peter Zyczynski 
<[EMAIL PROTECTED]> wrote:

Alright, the problem is definitely with joining on RowID from Table_A.

Got around this by creating a new column called _RowID in Table_A and
populated it with RowID, and join on that.
BUT a new problem arises, it appears the where clause is ignored - All 
rows
in Table_A  get updated, rather than just the ones limited to the where
clause.  Confused?  I am.

The code now looks like this:
'-----------------------------------
sub main
   ' Create a temporary _RowID column in Table_A.
   Alter Table "Table_A" ( add _RowID Integer )
   ' Populate the new _RowID field.
   Update Table_A Set _RowID = RowID
   ' Update Table_A with values from Table_B.
   Add Column Table_A (DestinationField)
      From Table_B
      Set To (SourceField)
      Where _RowID = MyID
   ' The above statement updates all records in
   ' Table_A, rather than just where they join to Table_B.
   ' Remove the temporary _RowID field.
   Alter Table "Table_A" ( drop _RowID )
end sub
'-----------------------------------
I was hoping to avoid doing any select queries and just do the operation 
in
one update query, got 200K+ records, also this operation will be run
regularly so the least number of select/update queries the better.

Cheers,
Peter Zyczynski
-----Original Message-----
From: Peter Zyczynski [mailto:[EMAIL PROTECTED]
Sent: Tuesday, 11 November 2003 2:52 PM
To: [EMAIL PROTECTED]
Subject: MI-L MBX - Add Column statement - MI crashes in a heap!
Help!

Trying to update "DestinationField" in "Table_A" with values from
"SourceField" in "Table_B", Mapinfo spits out the following error and 
shuts
down:

"The instruction at "0x00515248" referenced memory at "0x00080101". The
memory could not be "read".  Click OK to terminate, CANCEL to debug."
To keep things simple I whipped up this little sample:

'-----------------------------------
sub main
   Add Column Table_A (DestinationField)
      From Table_B
      Set To (SourceField)
      Where RowID = MyID
end sub
'-----------------------------------
I tried doing the above statement from within Mapinfo in the Mapbasic 
window
but the effect is the same - CRASHOLA!

I have a suspicion that its because I'm joining on RowID, ie:
    Table_A.RowID = Table_B.MyID
So, is it me, is it Mapinfo, or is it both of us?

Cheers,

Peter Zyczynski
Analyst Programmer
Insight GIS
Australia
Ph:  (03) 6234-5833
Fax: (03) 6234-5899
[EMAIL PROTECTED]
www.insightgis.com.au


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Robert Crossley
Agtrix P/L
9 Short St
New Brighton 2483
Far Southern Queensland
AUSTRALIA
153.549004 E 28.517344 S

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