[postgis-users] migrating tables to postgis

[John Callahan]

Thanks Mark.  This gives me a direction to go.  I have the correct SRS, and
your other points are valuable.  ST_GeomFromText is really what I was
missing.  Thanks.

The fact that I have two data tables to combine, would a View help here?  Or
somehow modify the SELECT statements that would go into the ST_GeomFromText
function?  (the examples only show hard-coded coordinates but I'm hoping a
SELECT statement can provide input.)

- John



On Tue, Jan 18, 2011 at 4:20 PM, MarkW <mark.wimer at gmail.com> wrote:

> Now that you have data in columns in Postgresql, you can use SQL statements
> to create your spatial data. Here are the steps:
> 1) identify your SRID/ spatial reference system
> 2) create geometries by passing your x and y with a spatial ref to the
> right function, and
> 3) add a row to the geometry_columns table so that other applications can
> more easily see the spatial data.
>
> 1) It's much easier if you can match your coordinate system to the right
> UTM srids in the spatial_ref_sys table; see spatialreference.org for help.
> 2) See this function:
> http://www.postgis.org/docs/ST_GeomFromText.html
> (and to prove it works, the reverse is ST_X or ST_Y) to get X,Y back out )
> 3)
> http://postgis.refractions.net/docs/ch04.html#Manual_Register_Spatial_Column
> (but also see the help under 'AddGeometryColumn (
> http://postgis.refractions.net/docs/AddGeometryColumn.html)
>
> Hope this helps.
>
> Mark
>
>
> On Tue, Jan 18, 2011 at 3:37 PM, John Callahan <john.callahan at udel.edu>wrote:
>
>> I apologize for asking what seems like an easy question.   I'm really just
>> getting started with PostGIS and not sure which way to go here.   I have a
>> two tables in MS Access format.  They are:
>>
>> Table1: StationID, easting, northing, elevation, etc...
>> Table2: StationID, data values...
>>
>> Table1 is basically an inventory of all our stations.  Table2 is a subset
>> that includes only stations we have certain data for.   How would I convert
>> these into a point data set (of Table2 stations) in PostGIS?   I was able to
>> copy the tables from Access into Postgres. Where would I go from here?
>> Maybe OGR would help going directly from Access (or text exports of Access)
>> into PostGIS?
>>
>> I am using Postgres 9.0.2/PostGIS 2.0.0 on Windows, and using Quantum GIS
>> for viewing.  Thanks for any guidance.
>>
>> - John
>>
>> **************************************************
>> John Callahan, Research Scientist
>> Delaware Geological Survey, University of Delaware
>> URL: http://www.dgs.udel.edu
>> **************************************************
>>
>>
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