结果 - 阵列不能强迫浮动（类型错误）

Question

我从数据库中检索的浮点值，并试图将其添加到浮点类型值，我得到一个错误：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是数组，如果结果可以有多个值，则应该使用tempPrice[0]，如果您确定它只有1个值，或者可以使用tempPrice.sum。

UPD： 尝试

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