Working with Database Structures - Learning MySQL - page 202

MEDIUMBLOB and MEDIUMTEXT
Identical to BLOB and TEXT , respectively, except that a maximum of 16,777,215 bytes
can be stored.
LONGBLOB and LONGTEXT
Identical to BLOB and TEXT , respectively, except that a maximum of four gigabytes
of data can be stored. The effective maximum can vary depending on the memory
available on the server and its configuration.
ENUM(' value1 '[,' value2 '[, ...]]
A list, or enumeration of string values. A column of type ENUM can be set to a value
from the list value1 , value2 , and so on, up to a maximum of 65,535 different values.
While the values are stored and retrieved as strings, what's stored in the database
is an integer representation. The enumerated column can contain NULL (stored as
NULL ), the empty string '' (stored as 0 ), or any of the valid elements (stored as 1 , 2 ,
3 , and so on). You can prevent NULL values from being accepted by declaring the
column as NOT NULL when creating the table.
This type is a compact way of storing values from a list of predefined values, such
as state or country names. Consider this example using fruit names; the name can
be any one of the predefined values Apple , Orange , or Pear (in addition to NULL and
the empty string):
mysql> CREATE TABLE fruits_enum ( fruit_name ENUM('Apple', 'Orange', 'Pear') );
Query OK, 0 rows affected (0.00 sec)
mysql> INSERT INTO fruits_enum VALUES ('Apple');
Query OK, 1 row affected (0.00 sec)
If you try inserting a value that's not in the list, MySQL warns you that it didn't
store the data you asked:
mysql> INSERT INTO fruits_enum VALUES ('Banana');
Query OK, 1 row affected, 1 warning (0.00 sec)
mysql> SHOW WARNINGS;
+---------+------+-------------------------------------------------+
| Level | Code | Message |
+---------+------+-------------------------------------------------+
| Warning | 1265 | Data truncated for column 'fruit_name' at row 1 |
+---------+------+-------------------------------------------------+
1 row in set (0.00 sec)
Similarly, a list of several allowed values isn't accepted either:
mysql> INSERT INTO fruits_enum VALUES ('Apple,Orange');
Query OK, 1 row affected, 1 warning (0.00 sec)
mysql> SHOW WARNINGS;
+---------+------+-------------------------------------------------+
| Level | Code | Message |
+---------+------+-------------------------------------------------+
| Warning | 1265 | Data truncated for column 'fruit_name' at row 1 |