下面哪一个是MySQL查询语句的正确执行顺序:
下面哪一个是MySQL查询语句的正确执行顺序:
SELECT ---> FROM(including JOINs) ---> WHERE ---> GROUP BY ---> HAVING ---> DISTINCT ---> ORDER BY ---> LIMIT/OFFSET
SELECT ---> DISTINCT ---> FROM(including JOINs) ---> WHERE ---> GROUP BY ---> HAVING ---> ORDER BY ---> LIMIT/OFFSET
FROM(including JOINs) ---> WHERE ---> GROUP BY ---> HAVING ---> SELECT ---> DISTINCT ---> ORDER BY ---> LIMIT/OFFSET
FROM(including JOINs) ---> WHERE ---> GROUP BY ---> HAVING ---> DISTINCT ---> SELECT ---> ORDER BY ---> LIMIT/OFFSET
SELECT的时候如果遇到重复数据,就需要去重,即使用DISTINCT;