SQL执行顺序

　　我们自己锁预想的SQL语句的执行顺序与实际的SQL语句的执行顺序是有区别的，因为mysql有这自带的优化器。

　　人写SQL语句

select
    <select_list>
from
    <left_table> <join_type>
    join <right_table> on <on_condition>
where
    <where_condition>
group by
    <group_by_condition>
having
    <having_condition>
order by
    <order_by_condition>
limit
    <limit_number>

　　机读的SQL顺序

from <left_table> 
    on <join_condition>
    <join_type> join <right_table>
where   
    <where_condition>
group by
    <group_by_condition>
having
    <having_condition>
order by
    <order_by_condition>
limit
    <limit_number>

　　记录一下学习笔记，若有错误还请大家指出