php - What is the best sub string making method? -

i need develop search program search specific content in database. part of matched content should shown brief search result.

here approaches make sub string search results

1. do database level sub string (mysql)
2. do sub string using php.

search field contains more 500 words (minimum). content feed via ck editor. there 65k rows in table , can grow. table contains 3 fields of strings values use search (content_title, short_description, detailed_description).

what efficient method sub string?