49. Define the following:

1. Partial Keys

Ther are the set of attributes that uniquely detects the weak entities related to the same owner entity.

2. Alternate Keys

This can be defined as all candidate keys except the primary key.

3. Compound Key

This contains multiple fields that enable the user to uniquely recognizing a specific record.

4. Artificial Key

This refers to the extra attribute added to the table when there are no stands alone or compounds key is available.