sql - 将 % 添加到成本价格并创建新列

Question

我有一列成本价格和一列零售价格，但该列是一个计算字段，成本价格 + 35%，所以我想编写一个自动更新零售价格的选择语句，但只是想不出该怎么做。你能帮我吗。

Cost Price      Retail Price
   35
   45
  125
   35

DECLARE @OrderNumber varchar (30)
DECLARE @OrderDate int
DECLARE @OrderLineNumber varchar(50)
DECLARE @CustomerSkey int
DECLARE @ProductSkey int
DECLARE @OrderMethodSkey int
DECLARE @Quantity int
DECLARE @Cost Decimal(18,3)


SET @OrderNumber = 1
SET @OrderDate = 0
SET @OrderLineNumber = 1
SET @CustomerSkey = 1
SET @ProductSkey = 1
SET @OrderMethodSkey = 1
SET @Quantity = 1
SET @Cost = 1


WHILE @OrderNumber <= 100
WHILE @OrderDate <= 100
WHILE @OrderLineNumber <= 100
WHILE @CustomerSkey <= 100
WHILE @ProductSkey <= 100
WHILE @OrderMethodSkey <= 100
WHILE @Quantity <= 100
WHILE @Cost <= 100



BEGIN
INSERT INTO Orders 
(OrderNumber
, OrderDate
, OrderLineNumber
, CustomerSkey
, ProductSkey
, OrderMethodSkey
, OrderTime
, Quantity
, Cost
, Price)

SELECT 
'ORD' + Right ('000000' + CAST (@OrderNumber AS varchar (30)), 6)
,DATEADD (day, CAST (RAND () * 1500 as int), '2008-1-1')
,(Right ('0' + CAST (@OrderLineNumber AS varchar (30)), 6))
,(99 * RAND()) + 1
,(99 * RAND()) + 1
,(2 * RAND()) + 1
,DATEADD(ms, cast(86400000 * RAND() as int), convert(time, '00:00'))
,(190 * RAND()) + 10
,(40 * RAND()) + 10
,@Cost + (@Cost * .35)



SET @OrderNumber = @OrderNumber + 1
SET @OrderDate = @OrderDate + 1
SET @OrderLineNumber = @OrderLineNumber + 1
SET @CustomerSkey = @CustomerSkey + 1
SET @ProductSkey = @ProductSkey + 1
SET @OrderMethodSkey = @OrderMethodSkey + 1
SET @Quantity = @Quantity + 1
SET @Cost = @Cost + 1


END

Answer 1

使用以下公式将其设为计算列：

CostPrice + (CostPrice * .35)

因此，每当您将新条目插入表时，CostPrice都会自动评估。

Answer 2

UPDATE TableName SET RetailPrice = CostPrice + (CostPrice * .35)

Answer 3

UPDATE Orders SET Price = Cost * 1.35

或者，如果您想将百分比设为变量：

UPDATE Orders SET Price = Cost * (1 + (@PERCENT / 100))

Answer 4

如果零售价总是等于成本价加上某个百分比，那么您可能想看看计算列是否有意义。

这是使用计算列定义的表的示例

CREATE TABLE TableName ( 
    CostPrice DECIMAL(18,4), 
    RetailPrice AS (CostPrice * 1.35)
);

但是，如果您无法定义或更改表架构，或者只是想更新所选行的零售价，那么您可以在使用 CostPrice 列中的值时更新 RetailPrice 列。

UPDATE TableName SET RetailPrice = CostPrice * 1.35

对于每一行，这将使用 CostPrice 来设置该行的 RetailPrice。WHERE如果要限制更新的行，而不是更新表中的每一行，还可以包含一个子句。