What are the functions of RLIKE in SQL?

In SQL, RLIKE is an operator used for regular expression matching, allowing users to search for specific patterns within text data. This operator is primarily used in MySQL databases and supports pattern matching using regular expressions. Some common functionalities include:

1. Search for strings containing a specific pattern in text data.
2. Search for strings in text data that begin or end with a specified pattern.
3. Search for strings that match a specified pattern in text data.
4. Special characters (such as ^, $, *, +, ?) can be used to represent different matching rules.
5. You can use character classes (such as [a-z], [0-9], etc.) to match specific ranges of characters.
6. You can extract matching content using grouping and capturing.
7. You can use backreferences to refer to previously captured content.
8. You can use quantifiers to specify the number of matches.
9. You can use a branching structure to match any one of multiple patterns.

In general, the RLIKE function can achieve complex text pattern matching operations, providing a variety of regular expression features to meet different needs.