MySQL in a Nutshell, 2nd Edition

Name

POSITION()

Synopsis

POSITION(substring IN string)

This function returns an index of the character in string where substring first appears. The first character of string is numbered 1. This function is like LOCATE(), except that the keyword IN is used instead of a comma to separate the substring and the containing string. Also, this function does not provide a starting point to begin the search; it must begin from the leftmost character. Here is an example:

UPDATE courses
SET course_name =
INSERT(course_name, POSITION('Eng.' IN course_name), 4, 'English')
WHERE course_name LIKE "%Eng.%";

In this example, some course names have the word English abbreviated as Eng. This SQL statement overwrites any such occurrences with the word English. It uses the POSITION() function to find the starting point of the abbreviation. The numerical value it returns is then used as the position argument for the INSERT() function (not the INSERT statement). If it’s not found, the course name will not be changed, because a value of 0 will be returned by POSITION(), and the INSERT() function ignores any request in which position lies outside the length of the original string.