MySQL OR operator
OR operator
MySQL OR operator compares two expressions and returns TRUE if either of the expressions is TRUE.
This function is useful in -
- It allows you to combine multiple conditions in a query, specifying that at least one of the conditions must be true for a record to be included in the result set.
- OR makes queries more explicit. It clearly states that you want records that meet one condition or another, which can help prevent misunderstandings or misinterpretations of your query.
- When you want to filter records based on multiple criteria, OR is crucial.
- By using OR judiciously, you can optimize your queries to efficiently retrieve the desired data.
- OR provides a way to logically combine conditions, allowing you to express complex logic in your queries.
- In some scenarios, OR can be used to conditionally insert or update records based on the presence of specific conditions.
- When you have complex conditions involving multiple logical operators like AND and OR, OR can be crucial for achieving the desired outcome.
Syntax:
OR, ||
When more than one logical operator is used in a statement, OR operators perform after AND operator. The order of evaluation can be changed by using parentheses.
The operator returns 1 when both operands are a non-NULL and one of them is nonzero and returns 0 when both operands are non-NULL and one of them is zero and returns NULL when one operand is NULL and other is zero and return 1 also when one is NULL and another operand is nonzero and NULL also when both operands and NULL.
MySQL Version: 8.0
Example: MySQL OR operator
The following MySQL statement satisfies the condition - "both operands are a non-NULL and one of them is nonzero", so it returns 1.
Code:
SELECT 5 || 5;
Output:
MySQL> SELECT 5 || 5; +--------+ | 5 || 5 | +--------+ | 1 | +--------+ 1 row in set (0.00 sec)
Example of MySQL OR operator with at least one (zero) 0
The following MySQL statement satisfies the condition - "both operands are non-NULL and one of them is zero", so it returns 1.
Code:
SELECT 5 || 0;
Output:
MySQL> SELECT 5 || 0; +--------+ | 5 || 0 | +--------+ | 1 | +--------+ 1 row in set (0.00 sec)
Example of MySQL OR operator when both operands are zero(0)
The following MySQL statement both of the operands are 0, so it returns 0.
Code:
SELECT 0 || 0;
Output:
MySQL> SELECT 0 || 0; +--------+ | 0 || 0 | +--------+ | 0 | +--------+ 1 row in set (0.00 sec)
Example of MySQL OR operator with at least one NULL operand
The following MySQL statement satisfies the condition - "one operand is NULL and other is zero", so it returns NULL.
SELECT 0 || NULL;
Output:
MySQL> SELECT 0 || NULL; +-----------+ | 0 || NULL | +-----------+ | NULL | +-----------+ 1 row in set (0.01 sec)
Example of MySQL OR operator with NULL and non-zero operand
The following MySQL statement satisfies the condition - "one operand is NULL and other is non-zero", so it returns 1.
Code:
SELECT 5 || NULL;
Output:
MySQL> SELECT 5 || NULL; +-----------+ | 5 || NULL | +-----------+ | 1 | +-----------+ 1 row in set (0.00 sec)
Example of MySQL OR operator with both NULL operands
The following MySQL statement both of the operands are NULL, so it returns NULL.
Code:
SELECT NULL || NULL;
Output:
MySQL> SELECT NULL || NULL; +--------------+ | NULL || NULL | +--------------+ | NULL | +--------------+ 1 row in set (0.00 sec)
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Next: XOR operator
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