Question

我有以下查询：

Declare @variable int
Set @variable = 10
select @variable = case
                        when max(max_val) >= @variable then @variable
                        else max(max_val)
                    end
from dsa_finaldataset
where account_id = 'a1'
and product_id = 'p1'
and product = 'x1'

select * from
(select *, row_number () over (partition by account_id, product_id,product order by revenue desc) as rk from
(select * from test_data
where account_id = 'a1'
and product_id = 'p1'
and product = 'x1'
and @variable between min_val and max_val)x)y
where y.rk =1;

这里我声明一个值设置为它的变量，并基于其中一个列值（max_val）我要么保留声明的值，要么将max_val列的值赋给变量。符合条件的记录将是查询输出。我对此提出的问题：

我有大约5种不同的产品，每种产品都有不同的min_val和max_val。但是，输入的变量将是相同的，并且在每个产品的情况下保持相同的条件。无论如何我可以使用循环结构，我可以在同一个查询中获得所有5个产品x1，x2，x3，x4和x5的输出，这样在评估变量条件和查询执行时，变量被重新分配其原始值，之后将检查条件并再次查询下一个产品？

Answer 1

根据我的理解，您可以将上述代码包含在一个函数中，其中product是一个参数（或者可能是all-account_id，product_id和product），并在此函数上使用APPLY运算符来获取所有数据你的产品：

CREATE FUNCTION dbo.fn_doCalculations (@account_id VARCHAR(10), @product_id VARCHAR(10), @product VARCHAR(10))
RETURNS @return TABLE (
        /* declare columns needed here */ 
    )
AS 
BEGIN
    Declare @variable int
    Set @variable = 10
    select @variable = case
                            when max(max_val) >= @variable then @variable
                            else max(max_val)
                        end
    from dsa_finaldataset
    where account_id = @account_id
    and product_id = @product_id
    and product = @product

    INSERT INTO @return (/* declared columns here */)
    select * 
    from 
    (   select *, row_number () over (partition by account_id, product_id,product order by revenue desc) as rk 
        from    (   select * 
                    from test_data
                    where account_id = @account_id
                        and product_id = @product_id
                        and product = @product
                        and @variable between min_val and max_val) x
                ) y
    where y.rk =1;

    RETURN
END

创建该功能后，您可以像这样查询以获得所有产品（或者只是您需要的产品）的结果：

SELECT *
FROM    dbo.your_products_table P
        OUTER APPLY dbo.fn_doCalculations(P.account_id, P.product_id, P.product)
WHERE   P.product_id IN ('x1', 'x2', 'x3', 'x4', 'x5')

这会将您的代码（功能）应用于您需要的产品。

SQL通过循环重置变量值

1 个答案: