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-- Students who are 'guest' members and have no overdue books
SELECT name, membership_type
FROM library_members
WHERE membership_type = 'guest' AND has_overdue_books = 'no';

-- Members who are 'guest' or borrowed more than 3 books
SELECT name, number_of_books
FROM library_members
WHERE membership_type = 'guest' OR number_of_books > 3;

-- Exclude members who have overdue books
SELECT name
FROM library_members
WHERE NOT has_overdue_books = 'yes';

# Logical Operators

Logical operators let you **combine multiple conditions** in a `WHERE` clause, making your filters more flexible and precise.

<br/>

## Main Logical Operators

| Operator | Description                         | Example                                                    |
| -------- | ----------------------------------- | ---------------------------------------------------------- |
| `AND`    | All conditions must be true         | `membership_type = 'student' AND has_overdue_books = 'no'` |
| `OR`     | At least one condition must be true | `membership_type = 'guest' OR number_of_books > 3`         |
| `NOT`    | Reverses or excludes a condition    | `NOT has_overdue_books = 'yes'`                            |

<br/>

## `AND` Operator Example

The `AND` operator filters rows where **all** conditions must be true.

```sql title="Filter: Students with no overdue books"
SELECT name, membership_type
FROM library_members
WHERE membership_type = 'student' AND has_overdue_books = 'no';
```

This query returns students who do not have any overdue books.

<br/>

## `OR` Operator Example

The `OR` operator filters rows where **at least one** condition is true.

```sql title="Filter: Guests or those with many books"
SELECT name, number_of_books
FROM library_members
WHERE membership_type = 'guest' OR number_of_books > 3;
```

This query returns either guests or anyone with more than 3 books checked out.

<br/>

## `NOT` Operator Example

The `NOT` operator filters out rows where the condition is true, returning only those that **do not match**.

```sql title="Filter: Exclude members with overdue books"
SELECT name
FROM library_members
WHERE NOT has_overdue_books = 'yes';
```

This query returns only members who do not have overdue books.

This query returns all library members who do not have overdue books.

Operator	Description	Example
`AND`	All conditions must be true	`membership_type = 'student' AND has_overdue_books = 'no'`
`OR`	At least one condition must be true	`membership_type = 'guest' OR number_of_books > 3`
`NOT`	Reverses or excludes a condition	`NOT has_overdue_books = 'yes'`

Logical Operators

Main Logical Operators

AND Operator Example

OR Operator Example

NOT Operator Example

What does the following query do?

`AND` Operator Example

`OR` Operator Example

`NOT` Operator Example