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[ : Character_class : Regular Expressions MySQL TUTORIALS

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[=character_class=] represents an equivalence class.

It matches all characters with the same collation value, including itself.

For example, if o and (+) are the members of an equivalence class, then [[=o=]], [[=(+)=]], and [o(+)] are all synonymous.

An equivalence class may not be used as an endpoint of a range.

The following table lists the standard class names.

alnum	Alphanumeric characters
alpha	Alphabetic characters
blank	Whitespace characters
cntrl	Control characters
digit	Digit characters
graph	Graphic characters
lower	Lowercase alphabetic characters
print	Graphic or space characters
punct	Punctuation characters
space	Space, tab, newline, and carriage return
upper	Uppercase alphabetic characters
xdigit	Hexadecimal digit characters


mysql> SELECT 'ABC' REGEXP '[[:alnum:]]+';
+-----------------------------+
| 'ABC' REGEXP '[[:alnum:]]+' |
+-----------------------------+
|                           1 |
+-----------------------------+
1 row in set (0.00 sec)

mysql>
mysql> SELECT 'ABC123' REGEXP '[[:alnum:]]+';
+--------------------------------+
| 'ABC123' REGEXP '[[:alnum:]]+' |
+--------------------------------+
|                              1 |
+--------------------------------+
1 row in set (0.00 sec)

mysql>