可以将数据库中所有表的主键作为一个表的外键引用吗？

Question

I am trying to make this demo database where I have tables like

Household(Primary key - hid)
People(Primary key - pepid)
ParChildOld(Primary key - pcoid)
Job(Primary key - empid)
School(Primary key - schlid)
Pension(Primary key - penid)  

Now I have various attributes about details of people in each household in different tables.

Can I take primary keys of all the tables and make one table, say AllKeys and reference them as foreign keys in this particular table?

ie:

AllKeys Table
Primary Key: AKid
-- Other columns include 
foreign keys- hid,pepid,pcoid,empid,schid,penid*

I don't know if this is silly to ask or not, but,

Is such a reference allowed? Can it be considered as a normalized form? Will the queries fired in this way joining AllKeys table and any other table(depending on query) work efficiently?

Answer 1

You could if all of those tables are related, but it would fail third and fourth normal forms, having both functional and multivalued dependencies in the table.

Consider the huge amounts of duplication required to store relationships for just a single household: One household (hid=1), two parents (pepid=1,2), two children (pepid=3,4), four parent-child relationships (pcoid=1,2,3,4), two jobs (empid=1,2), one school for both children (schlid=1) and two pensions (penid=1,2).

AKid | hid | pepid | pcoid | empid | schlid | penid
-----|-----|-------|-------|-------|--------|------
1    | 1   | 1     | 1     | 1     | null   | 1
2    | 1   | 1     | 2     | 1     | null   | 1
3    | 1   | 2     | 3     | 2     | null   | 2
4    | 1   | 2     | 4     | 2     | null   | 2
5    | 1   | 3     | 1     | null  | 1      | null
6    | 1   | 3     | 2     | null  | 1      | null
7    | 1   | 4     | 3     | null  | 1      | null
8    | 1   | 4     | 4     | null  | 1      | null

Another problem is that, assuming table ParChildOld contains a parent and a child column, you have no way of specifying whether for a pcoid reference in AllKeys, whether the pepid refers to the parent or the child.

In short, don't do it.

Answer 2

No, it will increase the complexities.

1. You will need to write extra code to maintain these FKs
2. Due to extensive DML operations the table may create deadlocks (depending on what DB Engine you're going to use) and your whole DB will stop responding because most of the queries will be depending on this table

Keep the data in normalized form and put your efforts on the queries and maintain it.

You should be more focus on proper indexing on your tables (according to how you're going to query them).

David Scarlett has defined it with a very nice example.