MySQL 的操作顺序？

Question

是否有明确的地方可以找到 mySQL 语句的操作顺序？以下顺序正确吗？

FROM 子句WHERE 子句GROUP BY 子句HAVING 子句选择子句ORDER BY 子句

如果是这种情况，我可以在 group by 子句中使用在 SELECT 子句(select first_name as "f_name")中定义的术语吗？

谢谢!

Answer 1

根据 MySQL documentation，我假设您对 SELECT 感兴趣语法如下

SELECT
[ALL | DISTINCT | DISTINCTROW ]
  [HIGH_PRIORITY]
  [STRAIGHT_JOIN]
  [SQL_SMALL_RESULT] [SQL_BIG_RESULT] [SQL_BUFFER_RESULT]
  [SQL_CACHE | SQL_NO_CACHE] [SQL_CALC_FOUND_ROWS]
select_expr [, select_expr ...]
[FROM table_references
[WHERE where_condition]
[GROUP BY {col_name | expr | position}
  [ASC | DESC], ... [WITH ROLLUP]]
[HAVING where_condition]
[ORDER BY {col_name | expr | position}
  [ASC | DESC], ...]
[LIMIT {[offset,] row_count | row_count OFFSET offset}]
[PROCEDURE procedure_name(argument_list)]
[INTO OUTFILE 'file_name' export_options
  | INTO DUMPFILE 'file_name'
  | INTO var_name [, var_name]]
[FOR UPDATE | LOCK IN SHARE MODE]]

是的，您可以在 GROUP BY 子句中使用用 AS 定义的列。