Query design for Category and Hazard Selection

In this sample database there are three tables:
1 – tblAHA
2 – tblHazard
3 – tblProject

Please see attached image

The following two tables have the seven Categories of Hazards:
1 – tblAHA
2 – tblHazard

The seven Categories of Hazards are:
1 – Physical
2 – Chemical
3 – Biological
4 – Environmental
5 – Radiological
6 – Natural
7 – Ergonomic

I am trying to create a query (no code, I don’t understand it) that displays “Hazards” from based on the Categories the user selects.

A user selects Physical as the Hazard Category. Contained in the Physical Hazard Category are the following physical hazards:
1 – Slip
2 – Trip
3 – Fall

Based on this example, only the Physical Hazards (Slip, Trip & Fall) would be displayed.

Who is Participating?
Scott McDaniel (Microsoft Access MVP - EE MVE )Connect With a Mentor Infotrakker SoftwareCommented:
I made some changes to this, and added a form (Form1) to show you how the relationship works.

If you need an interface utility that would allow users to select/deselect Hazards for each AHA record, then you'll probably be best advised to make use of a Temporary table where you can implement a checkbox sort of thing. This is a UI consideration that many users expect to see, and it's not too hard to do in Access (however, you must be somewhat fluent in VBA to impelment it).

At the end of the day, you want to relate your AHA record with multiple Hazards, and that is done through the AHA_Hazards table I've included. How you get that data into the table is the real trick!
Jeffrey CoachmanMIS LiasonCommented:
<I am trying to create a query (no code, I don’t understand it)>
A statement like this will generally limit your options, as somethings can only be done via code.

In any event...
It is not clear if your 3 "Physical hazards" are stored in a related table...

But the concept you are looking for here seems to be "Cascading Lists"
(Note that this concept relies on some VBA code, so I can't tell you that you will ever find a solution that is "100% Query", because in most cases you will need to "requery" the second list, AFAIK, you can only do this via VBA)
See some examples here:

plummetConnect With a Mentor Commented:
HI cssc1

It seems to me that your data structure is not appropriate for your requirements. From what I understand I think you need 2 tables: tblProject and tblHazardCategory

tblProject would be as you currently have it.
tblHazardCategory would have a HazardID, CategoryName and subCategoryName:
ID  CategoryName   SubCategoryName
1    Physical              Slip
2    Physical              Trip
3    Physical              Fall
4    Chemical            (etc, etc)

tblProject would simply link to the selected hazard.

However, you may want more than one hazard to be linked to a project, in which case you could have a 3rd table which contains a link to the project, and to the hazardcategory. That will allow as many hazards as the user requires to be linked to the project.

eg tblHazardProjectLink

Does that help? I hope so.

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Scott McDaniel (Microsoft Access MVP - EE MVE )Infotrakker SoftwareCommented:
We've been over this one before.

As plummet indicates (and as I said in your earlier question), you must implement a structure where you have tables to store both the Hazard and the Category, and you must relate your Hazard to the Category it belongs to. I personally would do it like this:



So you'd have data in tblHazardCategory like this:
ID    CatName
1       Physical
2       Chemical
3       Biological
etc etc

Open in new window

And data in tblHazard like this:
ID   Hazard    HazardCatID
1       Slip           1
2       Fall           1
3       Spill          2
4       Rupture    2
etc etc

Open in new window

You'd then relate ONLY the Hazard to the AHA record (using a Join table, as previously discussed).

In your form, you'd have a Subform based on the Join table. In that subform, you'd present a method where the user could filter for a specific HazardCategory (perhaps you'd have a combobox to do this, where the user would select a Category). After the user selects that Category, you'd then filter a second combobox so that only those Hazards associated with that Category would be presented. There are several different ways to do this, of course, but a simple datasheet form based on your Join table works well.

cssc1Author Commented:
I made the changes you suggested. I am not sure if I did it correctly because things don't seem to work correctly. For example:
1. I can't get the "Category' field in the tblCategory table to showup
2. Not sure if I have the correct Primary Keys in the Category and Hazard tables.
3. No way for users to select the Pre-loaded Hazards that populate the various Hazard Categories.
Scott McDaniel (Microsoft Access MVP - EE MVE )Infotrakker SoftwareCommented:
Are you referring to my comment? If so, I downloaded your file and looked, and your table structure isn't really what I suggested, nor is your form setup in a way where you could easily add Hazards to an AHA record.

What are "preloaded hazards"?
cssc1Author Commented:
  I re-did the tables and tried to do them exactly as you said, but now I don't know what fields to connect to create the relationships.
Please advise.
Jeffrey CoachmanConnect With a Mentor MIS LiasonCommented:
(I'll let plummet and LSM take it from here to avoid confusion...)
I think LSM has got this well in hand, so unless I can be of any more assistance I'll leave it to him.

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