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i have a layer in QGIS "Network" with attribute table. I want to compare columns rows from each columns and create ine and fill it based on result from comparison. Untill now I did it with help in Excel: enter image description here

I'm looking for to this in QGIS with help of SQL query:

SELECT t1.*,

     CASE WHEN Rock_G_ID =
                `(SELECT Rock_G_ID`
                   ` FROM network t2`
               ` WHERE t2.rownum = t1.rownum - 1) THEN '1'`
     ELSE '-' END AS Class`
     FROM network t1`

This works for one column and can't get it for the both same time like the formula in Excel. How can I do this?

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  • Try looking into window functions, such as lead() and lag(). Those functions respecively look at the previous row and the next row's value :)
    – GHRF
    Apr 16, 2018 at 14:22
  • @GHRF thank you for your suggestion , can you give me an example
    – AED EDA
    Apr 17, 2018 at 8:11

1 Answer 1

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I Haven't had a chance to test this, but it should get you close...

 CASE 
    WHEN attribute(get_feature(  @layer_name,  "fid" ,  @row_number -1 ),  "Rock_G_ID" ) = "Rock_G_ID"
        THEN attribute(get_feature(  @layer_name,  "fid" ,  @row_number -1 ),  "NEWColumn" )
    WHEN attribute(get_feature(  @layer_name,  "fid" ,  @row_number -1 ),  "ID_G" ) = "ID_G"
        THEN attribute(get_feature(  @layer_name,  "fid" ,  @row_number -1 ),  "NEWColumn" ) + 1
    ELSE 
        1
 END
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  • thank you very much for your answer , i will test it tomorow
    – AED EDA
    Apr 26, 2018 at 12:39

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