12 replies to this topic

[Cartogirl]

I have two files that I want only to pull certain data from. I need to find the slope % that is equal to 0.5 degrees and greater in an area that is <=-49 and >=-65. When I use the following equation I end up with everything being selected. I know this is incorrect as I can clearly see that the area covered by the slope points is less than that of the Bathy Depth.

I have tried many different ways and still am not comming up with the correct statement. If I relate the tables will that work? If so how do I then select only the data that I need?
Any suggestions would be great.

Cheers

Robyn

"Depth" <= -49 OR "Depth" >= -65 AND "slope" >= .5

[Robert2009]

I have two files that I want only to pull certain data from. I need to find the slope % that is equal to 0.5 degrees and greater in an area that is <=-49 and >=-65. When I use the following equation I end up with everything being selected. I know this is incorrect as I can clearly see that the area covered by the slope points is less than that of the Bathy Depth.

I have tried many different ways and still am not comming up with the correct statement. If I relate the tables will that work? If so how do I then select only the data that I need?
Any suggestions would be great.

Cheers

Robyn

"Depth" <= -49 OR "Depth" >= -65 AND "slope" >= .5

Have you tried this way Depth" <= -49 OR "Depth" >= -65 OR "slope" >= .5 ? Change from AND to OR after 65 ?

Adios from Southern New Mexico

[François Goulet]

I'm not an SQL expert, but I'd try to query them "separately".

"AND" has a precedence over the OR so you should applied you "AND" criteria over each Depth. It should be something like:

("Depth" <= -49 AND "slope" >= .5) OR ("Depth" >= -65 AND "slope" >= .5)

[Cartogirl]

Thanks for the suggestions. The selection is still incorrect as all slope data was selected. I wonder if it is the files I am using that is causing the issues, would it be better to go back to the original joined bathy and slope files?
How do relates work? I know that they are good for this kind of situation where more than one field is needed ,so if I related them how would I then select from the two tables?

Thanks again

Cheers

Robyn

[François Goulet]

You could always make your selection in each file and then intersecting the results...

[Hans van der Maarel]

Assuming you mean "Depth between -49 and -65 and slope greater than .5":

("Depth" <= -49 AND "Depth" >= -65) AND "slope" >= .5

[Cartogirl]

I used the intersect tool and it seems to have selected the data needed. This was after trying each of the above statements. I am still not certain why none of them worked as they would generate all the data as selected, which again makes me think I did something incorrect when creating the new shape files that were then being looked at.

I now need to clip the point file with the classification area file and seem to only be generating a point file back.


Thanks for all the help.

Cheers

[frax]

Is this ArcGIS? Aren't you supposed to write the fields like [depth] and not quoted? The query builder in ArcGIS is quite ok, and usually works for me if I am not sure.

[josie]

Assuming 'depth' and 'slope' are fields:

Try

'depth' <=-49
AND 'depth >=-65
AND 'slope' = 0.5

[josie]

Just noticed Hans already suggested that actually. He is correct, it should work!

[frax]

Also - if it is ArcGIS - then I think you can do it in a (visual) multi-step process - do one select, and reselect out of that selection.

[dsl]

Is this ArcGIS? Aren't you supposed to write the fields like [depth] and not quoted? The query builder in ArcGIS is quite ok, and usually works for me if I am not sure.

Brackets are for geodatabases and quotes are for shapefiles if memory serves.

Cheers,
David

[Cartogirl]

Thanks to all the help and advice on solving this problem.
Things are moving along now and it was because of all your ideas and suggestions.

Cheers

Robyn