If anyone is going to try the approach described below, I apologize for a faulty memory...do not GROUP BY point, ORDER BY point...grouping gives you all the points, but only a single record from Table B, not what we needed.
Bob ----- Original Message ----- From: "Robert T. Wright" <[EMAIL PROTECTED]> To: "Data Directions" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Tuesday, February 17, 2004 9:17 PM Subject: Re: MI-L Radius Select (Solution via commercial product - Data Assistant) > Thank you for the directions... pun noted. > > I developed what may be a slightly more complicated approach this afternoon. > > The "problem" is that I have one table of geographic points, Table A, and I > wanted to generate a report that displays each of the points in Table A > together with the associated geographic points and related data from another > table, Table B, that are within 10 miles of each of 255 points in the first > table. One point in Table B is, in fact, within 10 miles of 25 or more > points in Table A. > > I "solved" the problem by creating a 10 mile buffer around each point in > Table A and using an SQL query to select points from the second table whose > obj was were entirely within the buffer obj. By grouping the SQL, by point > in Table A, I get a list with each of the 255 points in the first table and > the associated points from the second table that were within the 10 mile > buffer obj. I would like to avoid the necessity of going through the buffer > routine, but it appears to have worked. The benefit of this approach is > that it did all 255 at once. Of course, as the database in Table B changes, > I'll have to do it over and over, which is the downside of this approach. > Saving the buffers and SQL statement make it relatively simple...but not > automatic. > > I may try the Data Assistant as well...I do appreciate the help. > > Bob > ----- Original Message ----- > From: "Data Directions" <[EMAIL PROTECTED]> > To: "Robert T. Wright" <[EMAIL PROTECTED]>; > <[EMAIL PROTECTED]> > Sent: Tuesday, February 17, 2004 8:50 PM > Subject: Re: MI-L Radius Select (Solution via commercial product - Data > Assistant) > > > > Hi, > > > > You should download an evaluation copy of our MapInfo add-on, called Data > > Assistant. Data Assistant is a validation, querying and update utilty for > > MapInfo, utilising dialog boxes and pulldown menu items. > > > > In your instance (after DA installation), manually select a point from one > > table. Then you would select (from the MapInfo menu bar), Data Assistant > > > Object Analysis > Distances to Object, ensuring that you specify the > second > > table to generate the report for. A report will be produced listing the > > distance of each point from your selected point. In the Browser Window > that > > opens, you can then easily select the points of interest (and save if > > required). > > > > If you just want to say select the 15 points CLOSEST to the selected > point, > > use Data Assistant > Select Objects > Nearest Objects to Selected Object > > (and enter the 'x' number of closest objects to select). > > > > Finally, if you want an new table created of nearest objects, with > selected > > attributes from both tables, use Data Assistant > Quick Updates > Objects > to > > Nearest Objects > > > > You can download a trial version from www.datadirections.com.au and click > on > > the "Download" link. A 110 page PDF user manual (with detailed > descriptions) > > will also be installed in the installation subdirectory. > > > > Please contact me if you have further queries. > > > > Regards, > > > > Bill > > > > William Donaldson > > GIS Applications Manager > > > > email: [EMAIL PROTECTED] > > web: www.datadirections.com.au > > > > > ============================================================================ > > ----- Original Message ----- > > From: "Robert T. Wright" <[EMAIL PROTECTED]> > > To: <[EMAIL PROTECTED]> > > Sent: Tuesday, February 17, 2004 9:46 PM > > Subject: MI-L Radius Select > > > > > > Selecting points that are within a given distance of a known point is a > > relatively straight forward procedure using the Distance function. But it > > requires the manual entry of the x,y coordinates of center point and you > > have to be working with one table. > > What I would like to do is select all points in Table A that within a > > specified distance of a point in Table B. I would like to "select" at > point > > from Table B by in a Map view, then using SQL Select, select all of the > > points in Table A that are within a fixed distance of the selected point. > > Ideally, what I would like to do is to develop the capability of > generating > > a table or list of all features in Table A that are within a fixed > distance > > of every point in Table B, in a single pass, but I can work progressively > if > > necessary. The capability is available using the radius select tool...what > I > > would like to know is how to do it with SQL. > > > > Thanks in advance for any assistance. > > > > Bob Wright > > > > > > > > --------------------------------------------------------------------- > > List hosting provided by Directions Magazine | www.directionsmag.com | > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > For additional commands, e-mail: [EMAIL PROTECTED] > > Message number: 10491 > > > --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 10493
