# Using many-to-one relationship in QGIS

I am not very experienced with QGIS.

My goal is to visualize the changing "geography of death" of the Roman emperors over time. The essential available data is the year of death (AD) and the place of death, with the places of death in some cases being duplicated since different emperors died in the exact same place, e.g. Rome. What I have been unsuccessfully trying to achieve is to create a map that reflects two things simultaneously:

1. The points of the places of death are to be classified by size according to the number of deaths in each.
2. The points of the places of death are to be visualized differently depending on the century in which the death occurred, i.e. to group the unique values (years of death) within periods, in this case, centuries.

Attached is a screenshot of a part of my attribute table.

Here is one of the things I've tried with no result:

``````CASE WHEN "Year of death" BETWEEN 1 AND 100 THEN '1st century AD' WHEN "Year of death" BETWEEN 101 AND 200 THEN '2nd century AD' WHEN "Year of death" BETWEEN 201 AND 300 THEN '3rd century AD' WHEN "Year of death" BETWEEN 301 AND 400 THEN '4th century AD' ELSE 'Other'END
``````

PS I succeeded in writing the correct expression in order to group the years of death in the respective centuries:

``````enter CASE WHEN  "Year of death" < 100 THEN '1st century' WHEN  ("Year of death" >= 100 and  "Year of death" < 200) THEN '2nd century' WHEN  ("Year of death" >= 200 and  "Year of death" < 300) THEN '3rd century' WHEN  ("Year of death" >= 300 and  "Year of death" < 400) THEN '4th century' END
``````

Still not able to manage the many-to-one relationship ...

• If you have 5 deaths in Rome, 3 of which were in the first century and 2 in the second, it's not clear to me how the point Rome should be symbolized? I understand: "It will have the size corresponfing to 5 deaths." But how do you want to symbolize the centuries? Commented Mar 8, 2023 at 0:37
• I found a workaround using the Points Displacement option, which somewhat solves the problem, but I still feel like there should be a more elegant solution that eludes me due to my inexperience, rather than because it's inherently impossible. Commented Mar 8, 2023 at 6:42
• The abovementioned workaround is not the best possible solution for at least one reason: it seems that qgis2web fails to create a web application when I'm using Points Displacement. Otherwise, it works fine. Commented Mar 8, 2023 at 7:01