SQL將varchar轉換爲貨幣

Question

我試圖計算項目的總成本，並將該值轉換爲稱爲成本的新列。

在我的創建腳本中，值是字符，但數據類型是金錢。

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

什麼是你從concat()期待？ concat()返回一個字符串值，根據您輸入的值將是由空格分隔的三個金額值，例如， $1.00 $2.00 $0.50

將它與貨幣值比較會引發錯誤。也許你打算只是增加值？

(range_price + crust_surcharge + sauce_surcharge) as [cost] 

注意：不要使用字符串文字作爲別名。

---

此外，您的where子句進行比較來從組合的子查詢一個money數據類型的字符串文字（'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子句中使用列別名，你必須重複表達或從一個子查詢/派生表或其他經營者引用的表達。