Question

SELECT *,


SUM(

    b1.bit_sum_excl * b1.bit_quantity - 
    if(b1.bit_deduction_percentage = 1, (b1.bit_deduction / 100)*(b1.bit_sum_excl * b1.bit_quantity), b1.bit_deduction)

)  as _total_unconverted,

/*************** _total_unconverted * 0.15 as some_val; ****************/


FROM `bill_items` b1

LEFT JOIN clients_packing_list ON (b1.bit_cli_pack_list_id = clients_packing_list.cli_pack_list_id)


WHERE b1.bit_cli_bill_id = 1 OR b1.bit_cli_bill_id = 0

我希望能够添加表达式

_total_unconverted * 0.15 as _converted

进入选择。

目前它抱怨它不是专栏。

有没有办法做到这一点，还是我必须复制粘贴SUM代码并添加乘数？

Answer 1

您可以在查询中使用user defined variables和MySQL。

SELECT *,
(@total:=SUM(
    b1.bit_sum_excl * b1.bit_quantity - 
    if(b1.bit_deduction_percentage = 1, (b1.bit_deduction / 100)*(b1.bit_sum_excl * b1.bit_quantity), b1.bit_deduction)
))  as _total_unconverted,
(@total * 0.15) as _converted,
FROM `bill_items` b1
LEFT JOIN clients_packing_list ON (b1.bit_cli_pack_list_id = clients_packing_list.cli_pack_list_id)
WHERE b1.bit_cli_bill_id = 1 OR b1.bit_cli_bill_id = 0

编辑但是，这并不能保证以正确的顺序分配值。为了正确实现它，请参阅以下小例子：

SELECT @min_price:=MIN(price),@max_price:=MAX(price) FROM shop;
SELECT * FROM shop WHERE price=@min_price OR price=@max_price;

来自documentation的粘贴。

基本上，您首先分配值，然后根据值重新选择，以确保它们被正确分配。

Answer 2

无法在返回该列的查询的_total_unconverted列表中引用列别名SELECT。

您可以将查询包装在一组parens中，并将其作为内联视图引用，并且列别名将在外部查询中可用。

在此示例中，内部查询返回列foo，并且可以在外部查询中引用该列名：

SELECT v.foo
     , v.foo * 0.15 AS bar
  FROM ( SELECT SUM(col) AS foo FROM mytable ) v

但是它无法在内部查询的SELECT列表中引用foo。（MySQL确实允许在ORDER BY子句和HAVING子句中引用列别名。）

为避免内联视图的开销，您需要重复表达式。

SELECT *
     , SUM(b1.bit_sum_excl * b1.bit_quantity -
         IF(b1.bit_deduction_percentage = 1
           ,(b1.bit_deduction / 100)*(b1.bit_sum_excl * b1.bit_quantity)
           , b1.bit_deduction
         )
       ) AS _total_unconverted
     , SUM(b1.bit_sum_excl * b1.bit_quantity -
         IF(b1.bit_deduction_percentage = 1
           ,(b1.bit_deduction / 100)*(b1.bit_sum_excl * b1.bit_quantity)
           , b1.bit_deduction
         )
       ) * 0.15 AS some_val
  FROM `bill_items` b1
  LEFT
  JOIN clients_packing_list
    ON b1.bit_cli_pack_list_id = clients_packing_list.cli_pack_list_id
 WHERE b1.bit_cli_bill_id IN (0,1)

Answer 3

SELECT *,SOURCEQUERY._total_unconverted * 0.15 as some_val FROM
(
SELECT 
SUM(
    b1.bit_sum_excl * b1.bit_quantity - 
    if(b1.bit_deduction_percentage = 1, (b1.bit_deduction / 100)*(b1.bit_sum_excl * b1.bit_quantity), b1.bit_deduction)
)  as _total_unconverted
FROM bill_items AS b1
LEFT JOIN clients_packing_list ON (b1.bit_cli_pack_list_id = clients_packing_list.cli_pack_list_id)
WHERE b1.bit_cli_bill_id = 1 OR b1.bit_cli_bill_id = 0
) AS SOURCEQUERY

如何将sum的结果存储到可在查询中使用的标识符中？

3 个答案: