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I have a dataset of address points with their associated street name, in addition to a tab file of polygons covering a catchment. I want to know if there is a way of selecting polygons which have address points with different street names within them.
I am guessing that there is a way of using the count function in MapInfo but unsure how this works with character fields.
The MapBasic SQL dialect is rather restricted, but this is possible by using several temporary tables.
Assuming that the Points table has a column StreetName, and that the Catchments table has a unique ID value, these three SQL statements should work (enter them into the MapBasic window):
Select ID, StreetName
From Points, Catchments
Where Points.obj intersects Catchments.obj
Into temp noselect
Group By ID, StreetName
select ID, count(*)
from temp
into temp2 noselect
Group By ID
Select *
From Catchments
Where ID in (select ID from temp2 where count > 1)
