# MySQL AND operator

## AND operator

MySQL logical AND operator compares two expressions and returns true if both of the expressions are true.

This function is useful in -

- AND ensures that all conditions specified in a query must be true for a row to be included in the result set.
- It enables you to express logical relationships between conditions, such as "A AND B AND C" where all conditions must be satisfied.
- By using AND judiciously, you can optimize your queries to efficiently retrieve the desired data.
- In more advanced queries, especially those involving joins and subqueries, AND is used to establish relationships between different parts of the query.
- By using AND, you can refine your queries to retrieve a more specific set of results.
- When combined with UPDATE and DELETE statements, AND allows you to specify multiple conditions that must be met for the operation to be executed.
- It's useful for combining different filters based on various attributes or columns.

**Syntax:**

AND, &&

This operator returns 1 if all operands are nonzero and not NULL, 0 if one or more operands are 0, otherwise, NULL is returned.

**MySQL Version: 8.0**

**Example: MySQL AND operator**

In the following MySQL statement all the operands are non-zero (5 and 5) and both of them are not NULL, so logical and operator returns 1.

Code:

```
-- This SQL statement performs a logical AND operation on the number 5
-- Explanation: The query evaluates a logical AND operation between the number 5 and itself, returning the result of the operation.
SELECT 5 && 5; -- The SELECT statement is used to evaluate the expression '5 && 5' and return the result
```

**Explanation:**

- The SELECT statement is used to evaluate expressions and return the result.
- The && operator is a logical AND operator in MySQL.
- In the context of the expression 5 && 5:
- Any non-zero number is considered as TRUE.
- The logical AND operation returns TRUE if both operands are TRUE.
- Since 5 is a non-zero number, it is considered TRUE.
- TRUE && TRUE evaluates to TRUE, which is represented as 1 in MySQL.
- Therefore, the result of SELECT 5 && 5 is 1.

Output:

MySQL> SELECT 5 && 5; +--------+ | 5 && 5 | +--------+ | 1 | +--------+ 1 row in set (0.00 sec)

**Example of MySQL AND operator with zero input**

In the following MySQL statement, one of the operands is non zero (5 and 0), so logical and operator returns 0.

Code:

```
-- This SQL statement performs a logical AND operation between the number 5 and 0
-- Explanation: The query evaluates a logical AND operation between the number 5 and 0, returning the result of the operation.
SELECT 5 && 0; -- The SELECT statement is used to evaluate the expression '5 && 0' and return the result
```

**Explanation:**

- The SELECT statement is used to evaluate expressions and return the result.
- The && operator is a logical AND operator in MySQL.
- In the context of the expression 5 && 0:
- Any non-zero number is considered as TRUE.
- Zero (0) is considered as FALSE.
- The logical AND operation returns TRUE only if both operands are TRUE.
- In this case, 5 is TRUE (non-zero), and 0 is FALSE.
- TRUE && FALSE evaluates to FALSE, which is represented as 0 in MySQL.
- Therefore, the result of SELECT 5 && 0 is 0.

Output:

MySQL> SELECT 5 && 0; +--------+ | 5 && 0 | +--------+ | 0 | +--------+ 1 row in set (0.00 sec)

**Example of MySQL AND operator with NULL input**

In the following MySQL statement, one of the operands is non zero (5) and another one is NULL, so logical and operator returns NULL.

Code:

```
-- This SQL statement performs a logical AND operation between the number 5 and NULL
-- Explanation: The query evaluates a logical AND operation between the number 5 and NULL, returning the result of the operation.
SELECT 5 && NULL; -- The SELECT statement is used to evaluate the expression '5 && NULL' and return the result
```

**Explanation:**

- The SELECT statement is used to evaluate expressions and return the result.
- The && operator is a logical AND operator in MySQL.
- In the context of the expression 5 && NULL:
- Any non-zero number is considered as TRUE.
- NULL represents an unknown or undefined value in SQL.
- The logical AND operation returns TRUE only if both operands are TRUE.
- If any operand is NULL, the result of the logical operation is NULL because the truth value is unknown.
- In this case, 5 is TRUE (non-zero), but NULL is an undefined value.
- TRUE && NULL results in NULL.
- Therefore, the result of SELECT 5 && NULL is NULL.

Sample Output:

MySQL> SELECT 5 && NULL; +-----------+ | 5 && NULL | +-----------+ | NULL | +-----------+ 1 row in set (0.00 sec)

**Example of MySQL AND operator with zero and NULL input**

In the following MySQL statement, one of the operands is zero (0) and another one is NULL, so logical and operator returns 0.

Code:

```
-- This SQL statement performs a logical AND operation between the number 0 and NULL
-- Explanation: The query evaluates a logical AND operation between the number 0 and NULL, returning the result of the operation.
SELECT 0 && NULL; -- The SELECT statement is used to evaluate the expression '0 && NULL' and return the result
```

**Explanation:**

- The SELECT statement is used to evaluate expressions and return the result.
- The && operator is a logical AND operator in MySQL.
- In the context of the expression 0 && NULL:
- Zero (0) is considered as FALSE.
- NULL represents an unknown or undefined value in SQL.
- The logical AND operation returns TRUE only if both operands are TRUE.
- If one operand is FALSE, the result of the logical AND operation is FALSE, regardless of the other operand.
- In this case, 0 is FALSE and NULL is an undefined value.
- FALSE && NULL results in FALSE because FALSE AND anything is FALSE.
- Therefore, the result of SELECT 0 && NULL is 0.

Output:

MySQL> SELECT 0 && NULL; +-----------+ | 0 && NULL | +-----------+ | 0 | +-----------+ 1 row in set (0.00 sec)

**Example of MySQL AND operator with both inputs are NULL**

In the following MySQL statement, all the operands are NULL. So the operator returns NULL.

Code:

```
-- This SQL statement performs a logical AND operation between two NULL values
-- Explanation: The query evaluates a logical AND operation between NULL and NULL, returning the result of the operation.
SELECT NULL && NULL; -- The SELECT statement is used to evaluate the expression 'NULL && NULL' and return the result
```

**Explanation:**

- The SELECT statement is used to evaluate expressions and return the result.
- The && operator is a logical AND operator in MySQL.
- In the context of the expression NULL && NULL:
- NULL represents an unknown or undefined value in SQL.
- The logical AND operation returns TRUE only if both operands are TRUE.
- If any operand is NULL, the result of the logical operation is NULL because the truth value is unknown.
- In this case, both operands are NULL.
- NULL && NULL results in NULL because the logical AND operation with unknown values remains unknown.
- Therefore, the result of SELECT NULL && NULL is NULL.

Output:

MySQL> SELECT NULL && NULL; +--------------+ | NULL && NULL | +--------------+ | NULL | +--------------+ 1 row in set (0.00 sec)

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