ruby - 来自数据库的结果 - 无法将数组强制转换为 Float (TypeError)

Question

我从数据库中检索了一个 Float 值并尝试将其添加到 Float 类型值中，但出现错误：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，tempPrice[0]如果您确定它只有 1 个值，则应该使用，或者tempPrice.sum如果结果可以有多个值，则可以使用。

UPD：试试

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