1
Q
This set entered on 5-12-2014
5.2.14.1
- A PRIMARY KEY is:
A
a KEY FIELD that is in the same table that holds THE RECORDS IT IDENTIFIES.
2
Q
- In the INVOICE TABLE, what is the PRIMARY KEY?
A
the INVOICE NUMBER FIELD because it IDENTIFIES AN INVOICE RECORD. If you put the INVOICE NUMBER in the LINE ITEMS table, it is NOT a PRIMARY KEY THERE.
3
Q
- If you put the INVOICE NUMBER in the LINE ITEMS table, it is NOT a PRIMARY KEY there, it is:
A
a FOREIGN KEY.
4
Q
- What do FOREIGN KEYS do?
A
FOREIGN KEYS IDENTIFY RECORDS IN OTHER TABLES.
5
Q
- Where do you need to put the FOREIGN KEY?
A
When you have a ONE TO MANY RELATIONSHIP, you MUST put the FOREIGN KEY in the table ON THE “MANY” SIDE.
6
Q
- By looking at the ENTITY RELATIONSHIP DIAGRAM, how do you know where the FOREIGN KEY GOES?
A
When you see a CROW’S FOOT in the ER Diagram, you NEED a FOREIGN KEY in the TABLE TO WHICH IT IS ATTACHED.
7
Q
- In a ONE TO MANY RELATIONSHIP, where is the PRIMARY KEY?
A
It is ALWAYS on the “ONE” table. The FOREIGN KEY is ALWAYS on the “MANY” table.
