The Boolean operators AND, OR and NOT allow combining multiple search conditions to complex Boolean expressions.
The result of the Boolean operations is given in the following tables:
AND
AND |
true |
false |
unknown |
True |
true |
false |
unknown |
False |
false |
false |
false |
unknown |
unknown |
false |
unknown |
OR
OR |
true |
false |
unknown |
true |
true |
true |
true |
false |
true |
false |
unknown |
unknown |
true |
unknown |
unknown |
NOT
NOT |
true |
false |
unknown |
|
false |
true |
unknown |
<boolean expression> ::=
<boolean term>
|
SELECT * FROM employees |
Boolean Operations. The query selects all employees with a name starting with 'John' or with a salary not exceeding 50000 or with a name equal to 'Mary Jones'.