MySQL不能用作查詢

Question

SELECT 
employees.emp_id, 
employees.emp_name_en, 
employees.emp_name_ar, 
employees.emp_nike_name, 
employees.emp_basic_salary, 
employees.emp_aw_food, 
employees.emp_aw_car, 
employees.emp_aw_mobile, 
employees.emp_aw_trans, 
employees.emp_aw_housing, 

((`settings`.`set_value` * `employees`.`emp_basic_salary`)/100) AS insurance_ratio, 
(((((`employees`.`emp_aw_housing` + `employees`.`emp_aw_trans`) + `employees`.`emp_aw_mobile`) + `employees`.`emp_aw_car`) + `employees`.`emp_aw_food`) + `employees`.`emp_basic_salary`) - ((`settings`.`set_value` * `employees`.`emp_basic_salary`)/100) AS net_salary, 
    (net_salary/30) AS day_salary 
FROM 
employees , 
settings 
WHERE 
settings.set_key = 'insurance_ratio' 

[錯誤] 1054 - 在 '字段列表' 未知列 'net_salary'

我怎麼可以使用列 'net_salary'

Answer 1

但是你可以做什麼......

SELECT tab1.*, (tab1.net_salary/30) AS day_salary 
FROM (SELECT 
employees.emp_id, 
employees.emp_name_en, 
employees.emp_name_ar, 
employees.emp_nike_name, 
employees.emp_basic_salary, 
employees.emp_aw_food, 
employees.emp_aw_car, 
employees.emp_aw_mobile, 
employees.emp_aw_trans, 
employees.emp_aw_housing, 

((`settings`.`set_value` * `employees`.`emp_basic_salary`)/100) AS insurance_ratio, 
(((((`employees`.`emp_aw_housing` + `employees`.`emp_aw_trans`) + `employees`.`emp_aw_mobile`) + `employees`.`emp_aw_car`) + `employees`.`emp_aw_food`) + `employees`.`emp_basic_salary`) - ((`settings`.`set_value` * `employees`.`emp_basic_salary`)/100) AS net_salary 
FROM 
employees , 
settings 
WHERE 
settings.set_key = 'insurance_ratio') AS tab1 

Answer 2

是的，這是一個衆所周知的關於需要重複使用的大量計算列的痛苦。

select emp_id,emp_name_en,emp_name_ar,emp_nike_name,emp_basic_salary, 
emp_aw_food,emp_aw_car,emp_aw_mobile,emp_aw_trans,emp_aw_housing, 
(net_salary/30) AS day_salary 
FROM 
( SELECT 
    employees.emp_id, 
    employees.emp_name_en, 
    employees.emp_name_ar, 
    employees.emp_nike_name, 
    employees.emp_basic_salary, 
    employees.emp_aw_food, 
    employees.emp_aw_car, 
    employees.emp_aw_mobile, 
    employees.emp_aw_trans, 
    employees.emp_aw_housing, 

    ((`settings`.`set_value` * `employees`.`emp_basic_salary`)/100) AS insurance_ratio, 
    (((((`employees`.`emp_aw_housing` + `employees`.`emp_aw_trans`) + `employees`.`emp_aw_mobile`) + `employees`.`emp_aw_car`) + `employees`.`emp_aw_food`) + `employees`.`emp_basic_salary`) - ((`settings`.`set_value` * `employees`.`emp_basic_salary`)/100) AS net_salary 
    FROM 
    employees , 
    settings 
    WHERE 
    settings.set_key = 'insurance_ratio' 
) d;