What is the difference between AND and OR in MySQL?

The Difference Between AND and OR in MySQL

In MySQL, the AND and OR operators are used to combine multiple conditions in a WHERE clause or a HAVING clause. The main difference between these two operators is the way they evaluate the conditions and the resulting output.

AND Operator

The AND operator is used to combine multiple conditions, and it requires all the conditions to be true for the overall condition to be true. In other words, the AND operator returns true only when all the conditions are true.

Here's an example:

SELECT * FROM users 
WHERE age > 18 AND email IS NOT NULL;

In this example, the query will return only the rows where the age is greater than 18 and the email is not NULL.

OR Operator

The OR operator is used to combine multiple conditions, and it requires at least one of the conditions to be true for the overall condition to be true. In other words, the OR operator returns true when at least one of the conditions is true.

Here's an example:

SELECT * FROM users 
WHERE age > 18 OR email IS NOT NULL;

In this example, the query will return the rows where the age is greater than 18 or the email is not NULL.

Comparison Using a Mermaid Diagram

Here's a Mermaid diagram that visually compares the AND and OR operators:

graph LR A[Condition 1] --> C{AND} B[Condition 2] --> C C --> D[True] C --> E[False] A[Condition 1] --> F{OR} B[Condition 2] --> F F --> D[True] F --> E[False]

In the diagram, the AND operator requires both conditions to be true for the overall condition to be true, while the OR operator requires at least one condition to be true for the overall condition to be true.

Real-World Examples

To help you better understand the difference between AND and OR, let's consider some real-world examples:

Ordering a Meal:
- AND example: You want to order a burger and fries.
- OR example: You want to order a burger or a salad.
Booking a Flight:
- AND example: You want to book a flight that departs from New York and arrives in Los Angeles.
- OR example: You want to book a flight that departs from New York or Chicago.
Applying for a Job:
- AND example: You need to have a college degree and 5 years of experience to apply for this job.
- OR example: You can apply for this job if you have a college degree or 10 years of relevant experience.

In the examples above, the AND operator is used to combine multiple conditions that must all be true, while the OR operator is used to combine conditions where at least one must be true.