Master SQL for Data Analysis - Creating Tables - Constraints

The video tutorial explains various SQL constraints used to maintain data integrity in tables. It covers NULL value constraints, check constraints for data validation, unique constraints to ensure data uniqueness, primary keys as unique identifiers, and foreign keys for referential integrity between tables. Examples using Netflix data illustrate these concepts.

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

• To increase the speed of data retrieval

• To maintain data integrity

• To reduce storage space

• To enhance user interface

What happens if you try to insert a NULL value into a column with a NOT NULL constraint?

• The value is automatically converted to zero

• The row is inserted with a warning

• An error is generated

• The NULL value is accepted

Which keyword is used to define a check constraint in SQL?

• ENSURE

• VERIFY

• CHECK

• VALIDATE

What is the purpose of a unique constraint in a database?

• To enforce data type restrictions

• To ensure each value in a column is unique

• To allow duplicate values in a column

• To speed up data retrieval

How can you define a unique constraint for multiple columns?

• By using a single column constraint

• By using a table constraint

• By using a foreign key

• By using a primary key

What is a primary key in a relational database?

• A column that can have duplicate values

• A column that uniquely identifies each row

• A column that stores foreign data

• A column that can be NULL

What does a foreign key constraint ensure?

• That a column can have NULL values

• That a column matches values in another table

• That a column is indexed

• That a column is unique