結果 - 陣列不能強迫浮動（類型錯誤）

Question

我從數據庫中檢索的浮點值，並試圖將其添加到浮點類型值，我得到一個錯誤：in '+': Array cant be coerced into Float (TypeError)

total = 0.0 
db = SQLite3::Database.open "Checkout.sqlite" 

for i in 0..@items.length 
    tempPrice = db.execute "SELECT price FROM Products WHERE product_code = ?", @items[i] 
    total = total + tempPrice 
end 

Answer 1

total = 0.0 
db = SQLite3::Database.open "Checkout.sqlite" 

for i in 0..@items.length 
    db.execute("SELECT price FROM Products WHERE product_code = ?", @items[i]) do |row| 
     total = total + row[0] 
    end 
end 

Answer 2

tempPrice是數組，如果結果可以有多個值，則應該使用tempPrice[0]，如果您確定它只有1個值，或者可以使用tempPrice.sum。

UPD： 嘗試

total = 0.0 
db = SQLite3::Database.open "Checkout.sqlite" 

@items.each do |item| 
    db.execute("SELECT price FROM Products WHERE product_code = ?", item) do |row| 
     total = total + row[0] 
    end 
end