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Using QGIS 2.16.2 I would like to export the unique values in a shapefile string attribute field to a new database table (which would contain a single field listing the unique values). The Vector > Analysis Tools > List Unique Values tool correctly selects the unique values, but the only output option is an .html file. Is there some way to output to a .dbf, or .csv format?

The shapefile is a line format, so the Dissolve tool does not work (it requires a polygon input), as described in Getting list of distinct values from shapefile field using QGIS?

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Go to DB Manager -> Virtual Layers -> QGIS layers, click on SQL Window button (or press F2), and write the next SQL expression: 

SELECT DISTINCT your_field FROM your_layer ORDER BY your_field;

Once you get the result table, click on Load as new layer, uncheck Geometry column, and click on Load now!.

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Now you have a table layer in QGIS, which you can export with right click -> Save As... to a CSV file, for example.

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  • @ German Carrillo Thank you. Following your advice, I use this SQL expression: SELECT DISTINCT junk FROM 2015_08_01 ORDER BY junk; This error results: Query execution error on CREATE TEMP VIEW _tview AS SELECT DISTINCT junk FROM 2015_08_01 ORDER BY junk;: 1 - unrecognized token: "2015_08_01" FYI, 2015_08_01 is the shapefile name and junk is the string attribute field. What am I doing wrong?
    – Stu Smith
    Commented Sep 29, 2016 at 18:16
  • Your table name seems to be special (only numbers and underscores), so you need to use quotation marks. Try with "2015_08_01" in the SQL sentence.
    – Germán Carrillo
    Commented Sep 29, 2016 at 18:44
  • Note that there is also a button called "Add VIrtual Layer" in QGIS. You could use it to avoid opening the DB Manager.
    – Germán Carrillo
    Commented Sep 29, 2016 at 18:46
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2023 you can do this by 3 different ways

Step by step walk through each method click here

https://transparentgov.net/cleargov1/1180/how-to-find-unique-value-part-5-qgis

I prefer SQL method,

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