Composite Primary Key Cascading
-
11-06-2021 - |
Pergunta
Two fields, Building and Room, make up a unique primary composite key in my rooms table. The key validates and saves, etc.
I have a BLANK Objects table which has three fields which will make it unique (again a composite primary key). The tables are as follows:
ROOM TABLE
[Building] [Room]
01 101A
01 102
02 101A
OBJECT TABLE
[Building] [Room] [Number]
01 101A 1
01 101A 2
01 102 1
02 101A 1
How do I enforce referential integrity? When editing the relationships in MS Access' relationship tool, I get the following error: No unique index found for the referenced field of the primary table
. I know (by trying non-unique values) that the composite keys for the primary (Object) table is correct. What am I doing wrong? How do I set up the proper relationships and maintain integrity (as updates will be a gruelling challenge without them)?
Solução
You need to set up your key like so:
Note that the primary key for rooms is set to Building + Room and for Objects it is Building + Room + Numb (Number is a reserved word AFAIR)