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== Logical Operators==

Name
Description
AND, &&
Logical AND
NOT, !
Negates value
||, OR
Logical OR
XOR
Logical XOR
<p>In SQL, all logical operators evaluate to TRUE, FALSE, or NULL (UNKNOWN).</p>
<p>In MySQL, these are implemented as 1 (TRUE), 0 (FALSE), and NULL.</p>

== Logical operator with parenthesis==



<source lang="sql">
mysql>
mysql>
mysql> CREATE TABLE Books(
-> BookID SMALLINT NOT NULL PRIMARY KEY,
-> BookName VARCHAR(40) NOT NULL,
-> Category VARCHAR(15),
-> InStock SMALLINT NOT NULL,
-> OnOrder SMALLINT NOT NULL
-> );
Query OK, 0 rows affected (0.01 sec)
mysql>
mysql>
mysql> INSERT INTO Books VALUES (101, "Java", "Nonfiction", 12, 13),
-> (102, "MySQL", "Fiction", 17, 20),
-> (103, "Oracle", "Nonfiction", 23, 33),
-> (104, "VB.net", "Nonfiction", 32, 12),
-> (105, "www.sqle.ru", "Fiction", 6, 35),
-> (106, "Perl", "Fiction", 28, 14),
-> (107, "Php", NULL, 46, 3);
Query OK, 7 rows affected (0.00 sec)
Records: 7 Duplicates: 0 Warnings: 0
mysql>
mysql>
mysql> select * from Books;
+--------+----------------+------------+---------+---------+
| BookID | BookName | Category | InStock | OnOrder |
+--------+----------------+------------+---------+---------+
| 101 | Java | Nonfiction | 12 | 13 |
| 102 | MySQL | Fiction | 17 | 20 |
| 103 | Oracle | Nonfiction | 23 | 33 |
| 104 | VB.net | Nonfiction | 32 | 12 |
| 105 | www.sqle.ru | Fiction | 6 | 35 |
| 106 | Perl | Fiction | 28 | 14 |
| 107 | Php | NULL | 46 | 3 |
+--------+----------------+------------+---------+---------+
7 rows in set (0.00 sec)
mysql>
mysql> SELECT BookName, Category, InStock, OnOrder
-> FROM Books
-> WHERE InStock>20 AND (Category IS NULL OR NOT (Category="Fiction"))
-> ORDER BY BookName;
+----------+------------+---------+---------+
| BookName | Category | InStock | OnOrder |
+----------+------------+---------+---------+
| Oracle | Nonfiction | 23 | 33 |
| Php | NULL | 46 | 3 |
| VB.net | Nonfiction | 32 | 12 |
+----------+------------+---------+---------+
3 rows in set (0.00 sec)
mysql>
mysql> drop table Books;
Query OK, 0 rows affected (0.02 sec)
mysql></source>

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