Which key in another table is used to establish a relationship between two tables ?
A ) Secondary Key
B ) Primary Key
C ) Foreign Key ✅
D ) Composite Key
Explanation:
A Primary Key is a column (or a set of columns) in a database table that uniquely identifies each record (row) in that table.
A Secondary Key is a field (or combination of fields) in a database table that is not the primary key, but is used to search, filter, or retrieve data more efficiently. It does not uniquely identify records, and may allow duplicate and null values .
A Foreign Key is a column (or a set of columns) in a database table that creates a relationship between two tables by referencing the Primary Key of another table.
A Composite Key is a combination of two or more columns in a table that together uniquely identify a record. None of the individual columns can uniquely identify the row by itself — only the combination does.