Dick Meehan
Dick Meehan
Programming language:Whatever
2021-07-09 00:27:10
0
Q:

difference between primary key and foreign key

Alex Wells
Alex Wells
Code: Whatever
2021-09-03 12:47:26 
Primary Key :
It is unique column in every table in a database
It can ONLY accept;
    - nonduplicate values
    - cannot be NULL
Foreign Key: 
It is a column that comes from a different table and
using Foreign key tables are related each other
It is the primary key of another table
It can be duplicate or null for another table

Unique Key:
Only unique value and also can contain NULL
0
xiumai
xiumai
Code: Whatever
2021-01-15 06:31:36 
Primary Key :
It is unique column in every table in a database
It can ONLY accept;
    - nonduplicate values
    - cannot be NULL
Foreign Key: 
It is a column that comes from a different table and
using Foreign key tables are related each other
It is the primary key of another table
It can be duplicate or null for another table

Unique Key:
Only unique value and also can contain NULL
0

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