内容来自 极客时间 课程: SQL必知必会的阅读笔记.
SELECT的执行顺序
关键字的顺序
SELECT … FROM … WHERE … GROUP BY … HAVING … ORDER BY …
SELECT执行顺序(MySQL和Oracle基本相同)
FROM > WHERE > GROUP BY > HAVING > SELECT的字段 > DISTINCT > ORDER BY > LIMIT
执行顺序示例
SELECT DISTINCT player_id, player_name, count(*) as num # 顺序 5 FROM player JOIN team ON player.team_id = team.team_id # 顺序 1 WHERE height > 1.80 # 顺序 2 GROUP BY player.team_id # 顺序 3 HAVING num > 2 # 顺序 4 ORDER BY num DESC # 顺序 6 LIMIT 2 # 顺序 7