[SQL] Related Posts by Relevancy. Source: http://stackoverflow.com/a/11144559/851045

sql-related-post-by-relevancy.sql

# Note: Higher number equals higher priority
#       to indicate greater relevancy

SELECT *,
    (CASE WHEN attribute1_field = attribute1_value THEN 2 ELSE 0 END) +
    (CASE WHEN attribute2_field = attribute2_value THEN 1 ELSE 0 END) +
    (CASE WHEN attribute3_field = attribute3_value THEN 1 ELSE 0 END) AS priority
  FROM table_post
  WHERE (
    attribute1_field     = attribute1_value
    OR attribute2_field  = attribute2_value
    OR attribute3_field  = attribute3_value
  )
  ORDER BY priority DESC
  LIMIT 0 , 10