Hvordan tæller man antallet af forekomster af et bestemt ord i en MySQL-blob-tekst?

Prøv dette

SET @searchthis="lumia"; 
SELECT  CAST((LENGTH(`documents`.`file`) - 
              LENGTH(REPLACE(`documents`.`file`, @searchthis, ""))) /
              LENGTH(@searchthis) AS UNSIGNED
            ) AS searchthis_count
    FROM  documents ;