Giving the result of column calculation an alias name : Alias « Select Query « MySQL Tutorial

1. MySQL Tutorial
2. Select Query
3. Alias

mysql>
mysql> CREATE TABLE Topic(
    ->    TopicID     SMALLINT NOT NULL AUTO_INCREMENT PRIMARY KEY,
    ->    Name        VARCHAR(50) NOT NULL,
    ->    InStock     SMALLINT UNSIGNED NOT NULL,
    ->    OnOrder     SMALLINT UNSIGNED NOT NULL,
    ->    Reserved    SMALLINT UNSIGNED NOT NULL,
    ->    Department  ENUM('Classical', 'Popular') NOT NULL,
    ->    Category    VARCHAR(20) NOT NULL,
    ->    RowUpdate   TIMESTAMP NOT NULL
    -> );
Query OK, 0 rows affected (0.02 sec)

mysql>
mysql>
mysql> INSERT INTO Topic (Name,          InStock, OnOrder, Reserved, Department,   Category) VALUES
    ->                   ('Java',          10,      5,       3,        'Popular',    'Rock'),
    ->                   ('JavaScript',    10,      5,       3,        'Classical',  'Opera'),
    ->                   ('C Sharp',       17,      4,       1,        'Popular',    'Jazz'),
    ->                   ('C',             9,       4,       2,        'Classical',  'Dance'),
    ->                   ('C++',           24,      2,       5,        'Classical',  'General'),
    ->                   ('Perl',          16,      6,       8,        'Classical',  'Vocal'),
    ->                   ('Python',        2,       25,      6,        'Popular',    'Blues'),
    ->                   ('Php',           32,      3,       10,       'Popular',    'Jazz'),
    ->                   ('ASP.net',       12,      15,      13,       'Popular',    'Country'),
    ->                   ('VB.net',        5,       20,      10,       'Popular',    'New Age'),
    ->                   ('VC.net',        24,      11,      14,       'Popular',    'New Age'),
    ->                   ('UML',           42,      17,      17,       'Classical',  'General'),
    ->                   ('www.java2s.com',25,      44,      28,       'Classical',  'Dance'),
    ->                   ('Oracle',        32,      15,      12,       'Classical',  'General'),
    ->                   ('Pl/SQL',        20,      10,      5,        'Classical',  'Opera'),
    ->                   ('Sql Server',    23,      12,      8,        'Classical',  'General');
Query OK, 16 rows affected (0.00 sec)
Records: 16  Duplicates: 0  Warnings: 0

mysql>
mysql> select * from Topic;
+---------+----------------+---------+---------+----------+------------+----------+---------------------+
| TopicID | Name           | InStock | OnOrder | Reserved | Department | Category | RowUpdate           |
+---------+----------------+---------+---------+----------+------------+----------+---------------------+
|       1 | Java           |      10 |       5 |        3 | Popular    | Rock     | 2007-07-23 19:09:48 |
|       2 | JavaScript     |      10 |       5 |        3 | Classical  | Opera    | 2007-07-23 19:09:48 |
|       3 | C Sharp        |      17 |       4 |        1 | Popular    | Jazz     | 2007-07-23 19:09:48 |
|       4 | C              |       9 |       4 |        2 | Classical  | Dance    | 2007-07-23 19:09:48 |
|       5 | C++            |      24 |       2 |        5 | Classical  | General  | 2007-07-23 19:09:48 |
|       6 | Perl           |      16 |       6 |        8 | Classical  | Vocal    | 2007-07-23 19:09:48 |
|       7 | Python         |       2 |      25 |        6 | Popular    | Blues    | 2007-07-23 19:09:48 |
|       8 | Php            |      32 |       3 |       10 | Popular    | Jazz     | 2007-07-23 19:09:48 |
|       9 | ASP.net        |      12 |      15 |       13 | Popular    | Country  | 2007-07-23 19:09:48 |
|      10 | VB.net         |       5 |      20 |       10 | Popular    | New Age  | 2007-07-23 19:09:48 |
|      11 | VC.net         |      24 |      11 |       14 | Popular    | New Age  | 2007-07-23 19:09:48 |
|      12 | UML            |      42 |      17 |       17 | Classical  | General  | 2007-07-23 19:09:48 |
|      13 | www.java2s.com |      25 |      44 |       28 | Classical  | Dance    | 2007-07-23 19:09:48 |
|      14 | Oracle         |      32 |      15 |       12 | Classical  | General  | 2007-07-23 19:09:48 |
|      15 | Pl/SQL         |      20 |      10 |        5 | Classical  | Opera    | 2007-07-23 19:09:48 |
|      16 | Sql Server     |      23 |      12 |        8 | Classical  | General  | 2007-07-23 19:09:48 |
+---------+----------------+---------+---------+----------+------------+----------+---------------------+
16 rows in set (0.00 sec)

mysql>
mysql> SELECT Name, InStock+OnOrder-Reserved AS Available
    -> FROM Topic
    -> WHERE Name LIKE '%bach%'
    -> ORDER BY Name;
Empty set (0.00 sec)

mysql>
mysql> drop table Topic;
Query OK, 0 rows affected (0.00 sec)