How to extract a substring from a string at a given position using the SUBSTRING() functions?

SUBSTRING(str, pos, len) is a MySQL built-in function that returns a substring from a string starting at a given position for a given length. For example:

SET @str = 'dba.FYIcenter.com';

SELECT SUBSTRING(@str, 5, 9);
  -- +-----------------------+
  -- | SUBSTRING(@str, 5, 9) |
  -- +-----------------------+
  -- | FYIcenter             |
  -- +-----------------------+

Reference information of the SUBSTRING() function:

SUBSTRING(str, pos, len): substr
  Return a substring len characters long from string str, starting at
  position pos. It returns NULL if any of its arguments are NULL.

Arguments, return value and availability:
  str: Required. The string that will be extracted from.
  pos: Required. The starting position of the substring to extract.
  len: Optional. The length of the substring to extract.
  substr: Return value. The substring extracted.
  Available since MySQL 4.0.

Related MySQL functions:

• SUBSTR() - Synonym for SUBSTRING()
• MID() - Synonym for SUBSTRING()

⇒ SUBSTRING_INDEX() - Substring in Delimited String

⇐ SUBSTR() - Synonym for SUBSTRING()

⇑ MySQL Functions on Character String Values

⇑⇑ MySQL Function References