How to find a substring in a given list string using the FIND_IN_SET() function?

FIND_IN_SET(str, strlist) is a MySQL built-in function that searches for a substring in a given list string of comma separated substrings. For example:

SET @obj = 'Apple';

SELECT FIND_IN_SET(@obj, 'Orange,Banana,Apple');
  -- +------------------------------------------+
  -- | FIND_IN_SET(@obj, 'Orange,Banana,Apple') |
  -- +------------------------------------------+
  -- |                                        3 |
  -- +------------------------------------------+

Reference information of the FIND_IN_SET() function:

FIND_IN_SET(str, strlist) : idx
  Returns a value in the range of 1 to N if the string str is in the
  string list strlist consisting of N substrings. A string list is a
  string composed of substrings separated by , characters. If the first
  argument is a constant string and the second is a column of type SET,
  the FIND_IN_SET() function is optimized to use bit arithmetic. Returns 0
  if str is not in strlist or if strlist is the empty string. Returns NULL
  if either argument is NULL.

  This function does not work properly if the first argument contains
  a comma (,) character.

Arguments, return value and availability:
  str: Required. The substring to search for in the list string.
  strlist: Required. The list string of comma separated substrings.
  idx: Return value. The index of the substring in the list string.
  Available since MySQL 4.0.

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