Question

我从我的数据库中检索了一个Float值，并尝试将其添加到Float类型值，我收到错误：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

tempPrice是数组，如果您确定它只有1个值，则应使用tempPrice[0];如果结果可以有多个值，则可以使用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

Answer 2

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

数据库的结果 - 数组无法强制转换为Float（TypeError）

2 个答案: