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Everything you ever wanted to know about getting started with the SQL Server 2008 Spatial Data Types …

Everything you ever wanted to know about getting started with the SQL Server 2008 Spatial Data Types …. … on the cheap!!. Spatial Data - Intro.

Samuel
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Everything you ever wanted to know about getting started with the SQL Server 2008 Spatial Data Types …

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  1. Everything you ever wanted to know about getting started with the SQL Server 2008 Spatial Data Types … … on the cheap!!

  2. Spatial Data - Intro • In the past few years, spatial information has come into it’s own as a powerful tool in the battle for better business intelligence. The question is: how can you and/or your business leverage it? • This talk will provide a 1000 mile an hour overview of a fairly common scenario in which SQL Server 2008 Spatial could be used by many NZ businesses. • There are some gaps that need filling here and there, mainly due to my own lack of understanding of the subject matter. However the overall principal is sound, I have used it, and with a bit of research on your part, it could work for you too! • Using the following scenario, I aim to show you how to get started and realise the spatial data types potential with minimal cost, by using free (or at least, inexpensive) datasets and software. • The idea is that if you were ever interested in spatial data, this is something you could spend a few Friday arvos setting up and be able to show the boss some real business benefits as a result.

  3. Scenario: Mass Marketing Task • Client asks you to create a dynamic mail/email marketing campaign for a product/service based on customer demographic. • Client is (for example) an insurance company. • Insurance would be marketed differently depending on whether the customer lives in a wealthy area or an area where there are lots of young families. • Client provides 50K customer addresses, and some styling directives – you need to come up with a proposed solution as to how to manage the demographic component. • The remaining slides take us through the process of how to achieve this using SQL Server 2008.

  4. The Data Types • There are 2 new spatial data types with SQL Server 2008 called Geometry and Geography. They come with all versions of the product (except Compact?), including SQL Server Express and are implemented as a CLR data types in SQL Server. • Geometry: this data type represents data in a Euclidean (flat) coordinate system. • Geography: this data type represents data in a round-earth coordinate system. The SQL Server geography data type stores ellipsoidal (round-earth) data, such as GPS latitude and longitude coordinates. • Together these data types, provide almost all of the spatial data management and manipulation functionality of a full blown commercial GIS.

  5. Geocoding • I.e. getting your customer address data geo-referenced. • Free geo-coding services. Yahoo, Google, etc. These facilities are great for getting started with and can provide you with the ability to run some intriguing experiments with your geo-coded customer data, before you get more serious about your spatial data. • Yahoo and Google offer free* RESTful web-service APIs for geo-coding purposes, so you also get to try out your skills with XLINQ or the XML data type! • Adhoc Geo-coding: many organisations offer a geo-coding service. For a one-off fee, you provide them with a file of addresses; then they provide you with a list of coordinates. • NZ Post GeoPAF: for the more serious geo-coder. This is a subscription based dataset provided by NZ Post, that lists every address that has ever had mail delivered to it along with a geo-spatial coordinate. Includes ‘Meshblock_Identifier’ field … • Please do read the fine-print with these services – there are some caveats for corporate users.

  6. Digital Boundaries and Census Data: • This information is freely available from Statistics New Zealand. Link provided in this slide-stack … • The digital boundaries data provides a range of different geographic boundaries for NZ, including ‘Wards’, ‘Regional Councils’ and ‘Meshblocks’. • We are interested in the Meshblocks as this is what enables us to attach a geo-spatial component to our Census data.

  7. Coordinate Systems and SRIDs: • When you’re loading up a new record that contains a spatial data type field, you need to specify an SRID. • Once you have the data, depending on how you got it, you may need to run a conversion in order to get it into the same coordinate system. • For example, the Google Maps API returns data in the WGS84 (SRID 4326) coordinate system, which is also the default for the geography data type. • New Zealand Digital Boundaries data is only available in NZMG coordinate system. • The best approach I have found so far for local (NZ – e.g. with the Census data) use, is to convert everything into NZMG, then use the geometry data type with ‘0’ as the SRID.

  8. Digital Boundaries Data Format: • Format is one of the most common for Spatial Data: ESRI ‘Shapefile’ format. • This format is used by the Arc suite of GIS products and has an open specification (similar to Office 2007). • Many people have already written conversion programs that manage the transition of Shapefiles into other formats. • I used Morten Nielsen’s ‘Shape2SQL‘ to get my Boundary Data into SQL Server. This is a closed source, but free product. Works for me - trust it if you dare! • Remember to select ‘planar geometry’ and uncheck ‘set SRID’. You will definitely want to leave ‘Create Spatial Index’ checked.

  9. Data Formats – cont … How to get your Geo-Coded data into the database? -- create a table CREATE TABLE Your_GeoCoded_Address_Points (Delivery_Point_IDint, X_Coordinateint, Y_Coordinateint, GeoPoint geometry) -- pull the data into our spatially enabled table DECLARE GenericCursor INSENSITIVE CURSOR FOR SELECT ID, X_Coordinate, Y_Coordinate FROM Your_Raw_Spatial_Data OPEN GenericCursor DECLARE @dpid as int DECLARE @x as int DECLARE @y as int DECLARE @g geometry; FETCH NEXT FROM GenericCursor INTO @dpid, @x, @y WHILE @@FETCH_STATUS = 0 BEGIN SET @g = geometry::STPointFromText('POINT (' + cast(@x as varchar(10)) + ' ' + cast(@y as varchar(10)) + ')', 0) INSERT INTO Your_GeoCoded_Address_Points (ID, X_Coordinate, Y_Coordinate, GeoPoint) values (@dpid, @x, @y, @g) FETCH NEXT FROM GenericCursor INTO @dpid, @x, @y END CLOSE GenericCursor DEALLOCATE GenericCursor -- create your spatial index CREATE SPATIAL INDEX SIndx_Your_GeoCoded_Address_Points_Geom ON Your_GeoCoded_Address_Points(GeoPoint) WITH ( BOUNDING_BOX = ( 2082369, 5356610, 2993453, 6744844 ) )

  10. Now What? • You’ve done the hard yards - collected your data into a big neat pile in the database, it’s all in the same format and is just itching to be queried … • Here’s where the power of the spatial data types starts to shine through. For the following queries, you’d want to use SSMS 2008 and keep an eye on the ‘spatial results’ tab …

  11. Pick a ‘Ward’ from the Meshblock Data: select * from dbo.MB06_LV2 where ward06 = 00704

  12. Pick a Meshblock from that Ward: select geom from dbo.MB06_LV2 where id = 30650

  13. Run a ‘Spatial Join’ query to get your addresses in that Meshblock: select GeoPoint.STBuffer(10) from Your_GeoCoded_Address_Points where geopoint.STWithin( (select geom from dbo.MB06_LV2 where id = 30650)) = cast(1 as bit)

  14. Thanks! …, etc … • …. then take a look at what goodies are available in the (free, publicly available) 2006 Census dataset. • I’ll leave the rest to your imagination. • Finally, if you’re serious about spatial data and don’t have a GIS background, I suggest you seek professional assistance before using this approach to make business decisions … • My details: • bernard.oleary@gmail.com • bernard-on-technology@blogspot.com

  15. Links: • NZ Digital Boundaries: http://www.stats.govt.nz/statistics-by-area/geography-mapping/download-digital-boundaries.htm • NZ Census Data: http://www.stats.govt.nz/census/census-outputs/meshblock/default.htm?tab=About • ESRI Shapefile Tech-Spec: http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf • SRIDs: http://msdn.microsoft.com/en-us/library/bb964707.aspx • Meshblocks: http://www.stats.govt.nz/statistics-by-area/geography-mapping/default.htm • Morten Nielsen’s Shape2SQL: http://www.sharpgis.net/page/Shape2SQL.aspx • Spatial Indexes in SQL Server 2008: http://msdn.microsoft.com/en-us/library/bb895265.aspx • Introducing SQL Server 2008 – free Microsoft Press E-Book book offer: http://csna01.libredigital.com/?urss1q2we6 • Geography Data type: http://msdn.microsoft.com/en-us/library/bb895266.aspx • Geometry Data Type: http://msdn.microsoft.com/en-us/library/bb895270.aspx • Manifold GIS: http://www.manifold.net/index.shtml

  16. Website: www.aucklandsql.com Mailing list: announce@aucklandsql.com

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