MySQL>=5.5:
SELECT FORMAT(10000000.5, 2, 'de_DE') AS format
MySQL<5.5:
SELECT REPLACE(REPLACE(REPLACE(FORMAT(10000000.5,2), ',', ':'), '.', ','), ':', '.') AS format
SELECT FORMAT(10000000.5, 2, 'de_DE') AS format
SELECT REPLACE(REPLACE(REPLACE(FORMAT(10000000.5,2), ',', ':'), '.', ','), ':', '.') AS format