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I have data symbolized with different categories Each category has a field for different symbology style like the table below. Is it possible to visualize the same category of data with in different styles without adding the layer twice?

I would like to do something like this
Category=Forest AND Symbology=1 THEN 'Green'
Category=Forest AND Symbology=2 THEN 'Blue'

In QGIS there is a selection "Data defined properties" with an expression builder, could it be done from it maybe?

Category Symbology
Forest 1
Forest 2
Shrub 1
Shrub 2
Grass 1
Grass 2

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Use Rule-based styling as in the following image, click on the "plus" icon to add more items:

Rule-based styling

Note the double-quotation marks for Field/Column names and single-quotation marks for strings. Although you don't need double-quotes for Field/Columns, I think it's good practice as it highlights what it is, useful for long logics but this is personal opinion :)

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    Just to agree, and to add that if having done this you save the style as a QGIS layer style file you can then access this style file with a text/xml editor... which can make setting up of a complex set of interrelated styles faster than doing it one by one directly in QGIS. – Rostranimin Jan 22 '15 at 13:56
  • @user27285, I save style files often but never edited one. But you're right in that it could save a lot of time. – Joseph Jan 22 '15 at 13:59
  • Thank you! That worked perfectly, never thought of rule based styling before, should have looked more carefully =) Good point about being able to edit the layer style files with an editor. – geogrow Jan 22 '15 at 14:17
  • The style file is an xml file. In case you aren't familiar with this take a moment to understand a few of the basics about what an xml file looks like (quick Google search) - QGIS uses these a lot, and familiarity with what they look like in general is helpful (the rest you can mostly work out from studying the file produced by QGIS). And try to use a text editor which is advanced enough to support you - one which will tell you if you make a mistake, or which will allow you to fold sections of the file and colour code the text. – Rostranimin Jan 22 '15 at 17:19
  • Is it anyone you can recommend? I have used Notepad++ a bit before, but that is also the only one – geogrow Jan 23 '15 at 10:22

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