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Manifold GIS allows the creation of dynamic drawings linked to queries.

Unfortunately I do not have access to Manifold as my employer refuses to pay for it, so am currently investigating alternatives.

Suppose I would like to buffer an alignment linestring stored in a database (SQL Server 2008), sample points at intervals around the buffer and then assign elevations to those points based on a raster:

  • With Manifold I would simply formulate this as a single nested query and link a drawing (vector layer) to it to contain the output, then if the alignment changes I just refresh the query and the linked drawing updates accordingly
  • With QGIS I can achieve the same result via a multiple step manual procedure (generating superfluous shapefiles along the way) each time the alignment changes, but this is nowhere near adequate for my requirements

Is there a more elegant way of combining functions in QGIS? If not, is this the sort of thing I might be able to achieve server side using PostGIS or similar? (I am completely ignorant of the workings of PostGIS).

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QGIS+PostGIS would be an efficient way to do the same procedure as the Manifold. Though it might be a steep learning curve formulating the SQL to start with. –  Mapperz Apr 5 '12 at 14:09
    
So the short answer is probably 'no' on the basis that QGIS lacks the sort of internal DBMS that Manifold possesses, and is only suitable for very basic join type data operations without writing your own python plugins? –  Will Apr 5 '12 at 15:08
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If you load the data into PostGIS, you can execute SQL statements on the data from within QGIS. There is a series of plugins that let you manage, query and visualize PostGIS data. Sextante for QGIS might also be an option in the future. –  underdark Apr 5 '12 at 16:12

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