Tutorials

My tutorials page is fairly dormant, which I apologize for. I'd like to add to it, but I've been busy. Also, the page is hosted on Google Pages, and it has been announced that Google Pages will be discontinued and migrated to Google Sites. I think having the tutorials on Google Sites will actually be better, but I'm not sure when this "migration" will actually happen. I just hope that I don't lose any of that work...

Find values in one table that are missing in another table MapInfo

Took me a little while to find an example of this, so I thought I would add one to the "interweb" to help other people.

One part of MapInfo that is extremely powerful is the SQL functionality. It isn't comprehensive, but there are a number of things you can do with it. Where I'm currently living/working (The Northern Territory) has a number of communities that could have several different names for the same location. This comes from communities named by European settlers in the area, and Indigenous names. Basically, you can have a spreadsheet of data that you want to tie to a geographic location via the name of an organisation, but the spreadsheet names might not necessarily match the database names that have the latitude and longitude. So I want to find out which values in the spreadsheet are "missing" from the database. In other words, which values did not join.

Two Tables: sdss_geography and tutorial_sample_2
Two Columns: sdss_geography.Organisation_Name and tutorial_sample_2.School

The first step is to perform a Join on the two tables. Using Query --> SQL Select

Select Columns: *
From Tables: sdss_geography, Tutorial_Sample_2
Where: sdss_geography.Organisation_Name = Tutorial_Sample_2.School
Ordered By: School
into Table Named: InitialJoin

Next go to File --> Save Query and save the InitialJoin query as a table. Then close the query table and load the InitialJoin.tab table.

Once the table is loaded, go back to Query --> SQL Select.

Select Columns: *
From Tables: Tutorial_Sample_2
Where: not School in (select School from InitialJoin)
Ordered By: School
into Table Named:MissingJoin

Click OK.

This produces a table of missing values. I take this table and make sure the name and spelling matches the central database.

Hopefully that helps someone else.

Programming Tutorials

I am creating a series of lessons to teach GIS Programming in an ArcGIS Environment.

Please visit the site here.

Please post your comments about the lessons at this post.

Hope you enjoy.





http://www.boxshapedworld.com/tutorials/ArcGIS%20Programming%20TOC.ashx