[MYSQL] 亂數隨機抽出 更有效率的語法 (RAND)

假設我們想隨機抽出三名中獎者，傳統寫法為：

SELECT * ORDER BY RAND( ) LIMIT 3

更有效率的寫法為

SELECT a . * FROM (
  SELECT a.no FROM mytable AS a ORDER BY RAND( ) LIMIT 3
) AS a2 INNER JOIN mytable AS a ON a.no = a2.no

速度會比傳統方法快。

參考資料 Q&A 、 mysql亂數取列-比order by RAND()快5倍！