원하는 row 수 만큼 뽑기.

출처 : http://mboy.tistory.com/49

MySQL
SELECT column FROM table ORDER BY RAND() LIMIT 1


PostgreSQL
SELECT column FROM table ORDER BY RANDOM() LIMIT 1


IBM DB2
SELECT column FROM table ORDER BY RAND() FETCH FIRST 1 ROWS ONLY


Oracle
SELECT column FROM ( SELECT column FROM table ORDER BY dbms_random.value ) WHERE rownum = 1


Microsoft SQL Server
SELECT TOP 1 column FROM table ORDER BY NEWID()