MySQL执行顺序

https://www.cnblogs.com/annsshadow/p/5037667.html

一、语法顺序

SELECT DISTINCT
     <select_list>
FROM
     <left_table> 
     <join_type> 
JOIN 
　　  <right_table> 
ON 
　　  <join_condition>
WHERE
     <where_condition>
GROUP BY
     <group_by_list>
HAVING
     <having_condition>
ORDER BY
     <order_by_condition>
LIMIT
<limit_number>

二、执行顺序

FROM 
　　<left_table>
ON
　　<join_condition>
　　<join_type>
JOIN
　　<right_table>
WHERE
　　<where_condition>
GROUP BY
　　<group_by_list>
HAVING 
　　<having_condition>
SELECT
DISTINCT
　　<select_list>
ORDER BY
　　<order_by_condition>
LIMIT
　　<limit_number>