Is a one column table good design? [closed]

Answer 1

Yes as long as the field is the primary key as you said it would be. The reason is because if you insert duplicate data those rows will be readonly. If you try to delete one of the rows that are duplicated. it will not work because the server will not know which row to delete.

Answer 2

All my tables have at least four tech fields, serial primary key, creation and modification timestamps, and soft delete boolean. In any blacklist, you will also want to know who did add the entry. So for me, answer is no, a table with only one column would not make sense except when prototyping something.

Answer 3

One case that I found sometimes is something like this:

Table countries_id, contains only one column with numeric ID for each country.

Table countries_description, contains the column with country ID, a column With language ID and a column with the localized country name.

Table company_factories, contains information for each factory of the company, including the country in Wich is located.

So to maintain data coherence and language independent data in the tables the database uses this schema with tables with only one column to allow foreign keys without language dependencies.

In this case I think the existence of one column tables are justified.

Edited in response to the comment by: Quassnoi

_{(source: ggpht.com)}

In this schema I can define a foreign key in the table company_factories that does not require me to include Language column on the table, but if I don't have the table countries_id, I must include Language column on the table to define the foreign key.

Answer 4

There would be rare cases where a single-column table makes sense. I did one database where the list of valid language codes was a single-column table used as a foreign key. There was no point in having a different key, since the code itself was the key. And there was no fixed description since the language code descriptions would vary by language for some contexts.

In general, any case where you need an authoritative list of values that do not have any additional attributes is a good candidate for a one-column table.

Answer 5

Yes that is perfectly fine. but an ID field couldn't hurt it right?

Answer 6

No problem as long as it contains unique values.