SQL将varchar转换为货币

Question

我试图计算项目的总成本，并将该值转换为称为成本的新列。

在我的创建脚本中，值是字符，但数据类型是金钱。

CREATE VIEW ordered_pizzas_view 
AS 
    SELECT 
     orderpizza_id, order_id, ..., 
     CONCAT(range_price, ' ', crust_surcharge, ' ', sauce_surcharge) AS 'cost' 
    FROM 
     order_pizza 
    INNER JOIN 
     ... 
    WHERE 
     'cost' = (SELECT SUM(CAST(range_price AS MONEY)) FROM pizza_range) + 
       (SELECT SUM(CAST(crust_surcharge AS MONEY)) FROM crust) + 
       (SELECT SUM(CAST(Sauce_surcharge AS MONEY)) FROM sauce) 

Answer 1

什么是你从concat()期待？ concat()返回一个字符串值，根据您输入的值将是由空格分隔的三个金额值，例如， $1.00 $2.00 $0.50

将它与货币值比较会引发错误。也许你打算只是增加值？

(range_price + crust_surcharge + sauce_surcharge) as [cost] 

注意：不要使用字符串文字作为别名。

---

此外，您的where子句进行比较来从组合的子查询一个money数据类型的字符串文字（'cost'）。

where --'cost' 
     (range_price + crust_surcharge + sauce_surcharge) 
       = (select Sum(CAST(range_price as money)) from pizza_range) 
      + (select Sum(CAST(crust_surcharge as money)) from crust) 
      + (select Sum(CAST(Sauce_surcharge as money)) from sauce) 

注意：您不能where子句中使用列别名，你必须重复表达或从一个子查询/派生表或其他经营者引用的表达。