How to locate a substring using the LOCATE() function?

LOCATE(substr, str, pos) is a MySQL built-in function that searches a substring in a string starting at a given position and returns the location of the substring. For example:

SET @str = 'Row, row, row your boat';

SELECT LOCATE('row', @str, 7);
  -- +------------------------+
  -- | LOCATE('row', @str, 7) |
  -- +------------------------+
  -- |                     11 |
  -- +------------------------+

Reference information of the LOCATE() function:

LOCATE(substr, str, pos): location
  Returns the position of the first occurrence of substring substr in
  string str, starting at position pos. Returns 0 if substr is not in str.
  Returns NULL if any argument is NULL.

Arguments, return value and availability:
  substr: Required. The substring to search for.
  str: Required. The string that will be searched in.
  pos: Optional. Default is 1. The position to start the search.
  location: Return value. The position where is substring is located.
  Available since MySQL 4.0.

Related MySQL functions:

• INSTR() - Find Substring
• POSITION() - Synonym for LOCATE()

⇒ LOWER() - Convert String to Lower Case

⇐ LENGTH() - Number of Bytes in String

⇑ MySQL Functions on Character String Values

⇑⇑ MySQL Function References