11、mysql的SQL执行顺序

编写顺序

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_params>

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_params>