This article covers the CHAR data type. See CHAR Function
for the function.
 
Syntax
------ 
[NATIONAL] CHAR[(M)] [CHARACTER SET charset_name] [COLLATE
collation_name]
 
Description
----------- 
A fixed-length string that is always right-padded with
spaces to the specified
length when stored. M represents the column length in
characters. The range
of M is 0 to 255. If M is omitted, the length is 1.
 
CHAR(0) columns can contain 2 values: an empty string or
NULL. Such columns cannot be part of an index. The CONNECT
storage engine does not support CHAR(0).
 
Note: Trailing spaces are removed when CHAR values are
retrieved
unless the PAD_CHAR_TO_FULL_LENGTH SQL mode is enabled.
 
Before MariaDB 10.2, all collations were of type PADSPACE,
meaning that CHAR (as well as VARCHAR and TEXT) values are
compared without regard for trailing spaces. This does not
apply to the LIKE pattern-matching operator, which takes
into account trailing spaces.
 
If a unique index consists of a column where trailing pad
characters are stripped or ignored, inserts into that column
where values differ only by the number of trailing pad
characters will result in a duplicate-key error.
 
Examples
-------- 
Trailing spaces:
 
CREATE TABLE strtest (c CHAR(10));
INSERT INTO strtest VALUES('Maria ');
 
SELECT c='Maria',c='Maria ' FROM strtest;
 
+-----------+--------------+
| c='Maria' | c='Maria ' |
+-----------+--------------+
| 1 | 1 |
+-----------+--------------+
 
SELECT c LIKE 'Maria',c LIKE 'Maria ' FROM strtest;
 
+----------------+-------------------+
| c LIKE 'Maria' | c LIKE 'Maria ' |
+----------------+-------------------+
| 1 | 0 |
+----------------+-------------------+
 
NO PAD Collations
 
NO PAD collations regard trailing spaces as normal
characters. You can get a list of all NO PAD collations by
querying the Information Schema Collations table, for
example:
 
SELECT collation_name FROM information_schema.collations 
 WHERE collation_name LIKE "%nopad%";
 
+------------------------------+
| collation_name |
+------------------------------+
| big5_chinese_nopad_ci |
| big5_nopad_bin |
...
 


URL: https://mariadb.com/kb/en/char/