[GIS] How to select distinct values from a column in Mapbasic

mapbasicmapinfosql

I have a table in a mapinfo .tab file. Is there any way to select distinct values from the column?

I tried :-

SELECT distinct (some_column) from table_name into temp_table

But this query would select all values. I wanted to select only distinct value from that column. Is there any way to achieve it?

Best Answer

MapInfo Pro does not support the Distinct keywork, unfortunately. However you can get to the same result just be grouping your result by the column

Select some_column from table_name into temp_table Group By some_column

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MapBasic – How to Remove Non-Alphanumeric Characters from String in MapBasic

Well that wasn't so hard.

Declare Sub Main
Declare Function RemoveSpecialChars(byval str as string) as String

Sub Main
    Dim t as string
    t = "this is a string with spaces and ' ! * & ^ % $ £ punctuation"

    Print Chr$(12) + "Original String: " + t
    Print "Tidy string: " + RemoveSpecialChars(t)

    End Program
End Sub

Function RemoveSpecialChars(byval str as string) as String
    Dim chr, out, nicechars as String
    Dim i, l as Integer

    nicechars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
    l = Len(str)

    For i = 1 to l
        chr = Mid$(str, i, 1)
        If InStr(1, nicechars, chr) > 0 Then
            out = out + chr
        End If
    Next

    RemoveSpecialChars = out
End Function

[GIS] How to select nth row in mapbasic

Select * from 'table' Where RowID = n

If you want it into a selection table of your choice, put the selection into somename, then browse * from somename If not, just Browse from selection

edit

This is all from memory, so please play about and also read the online reference manual:

MapBasic Ref

MapInfo -L

Best Answer

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MapBasic – How to Remove Non-Alphanumeric Characters from String in MapBasic

[GIS] How to select nth row in mapbasic

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