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Asked: 2026-06-18T10:30:51+00:00

I’m looking for a solution to storing and retrieving user entered data as a

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I’m looking for a solution to storing and retrieving user entered data as a drop down list.

The user wants to start with an existing drop list containing values of breeds.

Breed Select List

<select>
<option value="0">select</option>
<option value="1">Afghan Hound</option>
<option value="2">Airedale Terrier</option>
<option value="3">American Bulldog</option>
<option value="4">Belgian Malinois</option>
</select>

A breed Table exists

|breed_id|  breed_title   |
---------------------------
|   1    |  Afghan Hound  |
|   2    |Airedale Terrier|
|   3    |American Bulldog|
|   4    |Belgian Malinois|

The breed_id value will be saved with the pet values

|pet_id| pet_name | pet_sex |breed_id|
--------------------------------------
|  1   | 'Foo Foo'|   'M'   |    2   |
|  2   | 'Sparky' |   'f'   |    4   |
|  3   |  'Spot'  |   'M'   |    1   |

Because there are so many different types of breeds and because of the potential for entering erroneous breed types – The user wants to be able to add, edit and DELETE breed types.

I can see that I can edit and add breed types in/to the breed table. But what if the user deletes a breed, lets say breed #2:

|breed_id|  breed_title   |
---------------------------
|   1    |  Afghan Hound  |
|   3    |American Bulldog|
|   4    |Belgian Malinois|

The pets association to that breed is lost:

|pet_id| pet_name | pet_sex |breed_id|
--------------------------------------
|  1   | 'Foo Foo'|   'M'   |   (2)  |<<<<<<<
|  2   | 'Sparky' |   'f'   |    4   |
|  3   |  'Spot'  |   'M'   |    1   |

What do I do about the association between a pet that has a breed_id that has been deleted from the breed table?

The next time the pet is called and I try to populate the Breed Select List – breed #2 is gone. What do I do with that pets breed now? How do I populate my drop list now?

I can think of a few ways to handle this – but I am not sure of correct solution – or best practice.

I realize that there may be more a, logic or data entry method, type of solution. Whatever the solution is – I just want to know how the pro’s handle this sort of thing.

Thank you : )

Regards

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1 Answer

  1. Editorial Team

    How to handle dogs which reference deleted breeds would depend on why the breed needed to be changed.

    Each different reason will have a different outcome as they are trying to achieve different things. A few are:

    1. A breed was mis-spelt or renamed
    2. Two breeds are actually one
    3. An errant (non existant) breed was created

    I would suggest the following behaviour for each case

    1. Rename simply update the existing breed table, being able to do this is one of the primary motivations of normalising the breed data in the first place.

    2. Merging, If you decide ‘Afghan Hound’, and ‘Kuchi Hound’ are actually the same breed, then you would first change all the dogs which are referencing ‘Afghan Hound’ to instead reference ‘Kuchi Hound’ then you can delete the ‘Afghan Hound’ breed without worrying about dangling references.

    3. Delete, say a breed ‘Yo Mama’ was created, if you decide that the dogs which are of this breed type are also not desired, you can first delete all the dogs which reference ‘Yo Mama’ then the breed. If you wanted to keep the dogs, I would suggest creating an ‘unknown’ breed type, or making the breed NULLable, and set the breed of all the ‘Yo Mama’ dogs to NULL before deleting the breed.

    Either way, these outcomes will depend on the type of behaviour you want for you specific system, but I hope this gives you an idea of some common types of migrations.

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