A regular expression contains characters that represent source character types, source character sets, and string or word boundaries in the source columns. A regular expression can also contain quantifiers that determine how many times characters can occur in the source data. Regular expressions are case sensitive.
The following special characters are examples of characters that you can include in a regular expression:
Any character except [\^$.|?*+()
All characters except the listed special characters match a single instance of themselves. For example,
abc
always matches
abc.
\ (backslash) followed by any of the following special characters:
[\^$.|?*+(){}
A backslash escapes any special character in a regular expression, so the character loses the special meaning.
* (asterisk)
Matches the preceding token zero or more times.
[ (left bracket)
Marks the beginning of specifications for one character that you want to match.
- (hyphen)
Specifies a range of characters. For example, [a-zA-Z0-9] matches any letter or digit.
] (right bracket)
Marks the end of the specifications for one character.