MySql 1248 - Every derived table must have its own alias

 

執行一個sql語句，報錯：1248 - Every derived table must have its own alias

提示說每一個衍生出來的表，必須要有自己的別名

 

執行子查詢的時候，外層查詢會將內層的查詢當做一張表來處理，所以我們需要給內層的查詢加上別名

 

 錯誤的：

select count(*) from( select FROM_UNIXTIME(`user_task`.`CREATE_TIMESTAMP`, "%Y-%m-%d") FROM r_user_task `user_task` LEFT JOIN e_task `task` ON `user_task`.`TASK_ID` = `task`.`ID` where `user_task`.`COMPLETE_STATUS` = "1" and `user_task`.`user_id` = 175286 group by FROM_UNIXTIME(`user_task`.`CREATE_TIMESTAMP`, "%Y-%m-%d") ) 

 

正確的sql，應該加上別名，如下：

select count(*) from( select FROM_UNIXTIME(`user_task`.`CREATE_TIMESTAMP`, "%Y-%m-%d") FROM r_user_task `user_task` LEFT JOIN e_task `task` ON `user_task`.`TASK_ID` = `task`.`ID` where `user_task`.`COMPLETE_STATUS` = "1" and `user_task`.`user_id` = 175286 group by FROM_UNIXTIME(`user_task`.`CREATE_TIMESTAMP`, "%Y-%m-%d") ) as t

 

 

參考：

https://blog.csdn.net/cao478208248/article/details/28122113