Master SQL for Data Analysis - Primary and Foreign Keys

The video tutorial explains the concepts of primary and foreign keys in databases. Primary keys are unique identifiers for rows in a table, ensuring no duplicate entries. They can be a single column or a combination of columns. Foreign keys, on the other hand, are used to create relationships between tables by referencing primary keys in other tables. This helps maintain data integrity and prevents data duplication across tables. The tutorial provides examples of how these keys are used in relational databases to link tables and manage data efficiently.

What is the primary purpose of a primary key in a database table?

• To uniquely identify each row

• To encrypt data

• To store large amounts of data

• To connect multiple databases

When creating a new table, how do you specify which column will be the primary key?

• By marking it as a foreign key

• By using a unique constraint

• By specifically designating it as the primary key

• By setting it as the default column

How do foreign keys help in relational databases?

• They ensure all data is stored in one table

• They increase the speed of data retrieval

• They enable navigation between tables

• They allow for the encryption of data

What is a key difference between primary keys and foreign keys?

• Primary keys can be duplicated, foreign keys cannot

• Foreign keys must be unique, primary keys do not

• Foreign keys are used for encryption, primary keys are not

• Primary keys uniquely identify rows, foreign keys reference primary keys in other tables

In the context of foreign keys, what is a 'parent table'?

• A table that stores all data

• A table that is referenced by a foreign key

• A table that contains the foreign key

• A table that is not related to any other table