rank the fields of a query based on another field

[cardosan]

Dear all,
I have the query below that return a table like:
PLOTNR; period,Value, ID, Basal_area/ha, Basal_area/ha, perc_BA_sp

What I want to is to add another field that rank the perc_BA_sp by PLOTNR descending (thus highest perc_BA_sp values rank one etc.)
could someone help me out of this?

SELECT [INDENT][Q:INV1-Basal_area_plot-spp].PLOTNR, 
1 AS period, 
[Q:INV1-Basal_area_plot-spp].Value, 
[Q:INV1-Basal_area_plot-spp].ID, 
[Q:INV1-Basal_area_plot-spp].[Basal_area/ha], 
[Q:INV1-Basal_area_plot].[Basal_area/ha], 
([Q:INV1-Basal_area_plot-spp]![Basal_area/ha]/[Q:INV1-Basal_area_plot]![Basal_area/ha])*100 AS perc_BA_sp[/INDENT]
FROM
[INDENT][Q:INV1-Basal_area_plot-spp] INNER JOIN [Q:INV1-Basal_area_plot] 
[/INDENT]ON 
[INDENT][Q:INV1-Basal_area_plot-spp].PLOTNR = [Q:INV1-Basal_area_plot].PLOTNR
[/INDENT]
GROUP BY
[INDENT][Q:INV1-Basal_area_plot-spp].PLOTNR, 1, 
[Q:INV1-Basal_area_plot-spp].Value, 
[Q:INV1-Basal_area_plot-spp].ID, 
[Q:INV1-Basal_area_plot-spp].[Basal_area/ha], 
[Q:INV1-Basal_area_plot].[Basal_area/ha]
[/INDENT]
ORDER BY 
[INDENT][Q:INV1-Basal_area_plot-spp].PLOTNR, 
([Q:INV1-Basal_area_plot-spp]![Basal_area/ha]/[Q:INV1-Basal_area_plot]![Basal_area/ha])*100 DESC;
[/INDENT]

 

[jdraw]

See this example by Allen Browne