Mysql learns the order of execution of SQL

JSON query for MySQL:

1, a common SQL

SELECT      <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>

2. Mysql parsing Read sql

 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>

MySQL parses SQL first from the start, should be for he needs to know the data source those tables first.

Cartesian product: A table 10 B table 5, Cartesian product =10*5.

Mysql learns the order of execution of SQL