# Match String Pattern:  RLIKE
__*RLIKE operation*__
__*REGEXP operation*__
__*regular expression*__
+ Regular expressions are a powerful method to specify patterns for complex searches
+ **`RLIKE, REGEXP`** operator: **`expression RLIKE|REGEXP 'regexp-pattern'`**  
+ **`\`** As an escape character
+ **`()`** Group multiple regular expression elements
+ For example:
  + **`^`**: the beginning of the string
  + **`$`**: end of string
  + **`.`**: any single character
  + **`x*`**: zero or more **`x`**  
  + **`x+`**: one or more **`x`**  
  + **`x?`**: zero or one **`x`**  

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Other modes:
  **`|`**: Alternate
  **`{n}`** :n times
  **`{m,n}`** :m to n times
  **`[ ]`**: contains one character in square brackets
  **`[^ ]`**: Does not contain any of the characters in square brackets
  **`[[:class:]]`**: a character in a character class
For more information on regular expressions, see the URL at **`http://dev.mysql.com/doc/mysql/en/regexp.html`** .