What is the usage of regular expressions in MySQL?

In MySQL, regular expressions are used in queries for searching a pattern in a string.

• * Matches 0 more instances of the string preceding it.
• + matches 1 more instances of the string preceding it.
• ? Matches 0 or 1 instances of the string preceding it.
• . Matches a single character.
• [abc] matches a or b or z
• | separates strings
• ^ anchors the match from the start.
• "." Can be used to match any single character. "|" can be used to match either of the two strings
• REGEXP can be used to match the input characters with the database.

Example:

The following statement retrieves all rows where column employee_name contains the text 1000 (example salary):