From the course: Database Design Fundamentals

Unlock the full course today

Join today to access over 24,900 courses taught by industry experts.

What is a null?

What is a null?

From the course: Database Design Fundamentals

Start my 1-month free trial Buy for my team

What is a null?

“

- [Instructor] In database design, a NULL represents the absence of a value in a particular field or column. Imagine you're filling out a form and there's a question you don't have an answer to, so you leave it blank. In a database, that blank space is represented by a NULL. It's different from a zero, an empty string or any other value. NULL specifically means "no value." For example, if you're tracking someone's age, a value of zero means the person is a newborn, while NULL means their age is unknown. Special behavior in queries happen when you have a NULL. When you run searches or calculations in a database, NULL values are treated differently. For example, if you try to add numbers together and one of them is a NULL, the result will be a NULL value because the database can't calculate with a missing value. When designing a database, it's important to keep data integrity in mind at all times. It is easy to make a decision that you will make every field in your database mandatory so…

Contents