将变量赋给mysql查询ruby-Assignvariabletomysqlqueryruby

So I'm building a login/signup page in Ruby/Sinatra, and I'm trying to add some logic so that if someone tries to sign up with an email that is in use, it will tell them so, and not allow them to sign up

所以我正在Ruby / Sinatra中构建登录/注册页面，我正在尝试添加一些逻辑，以便如果有人尝试使用正在使用的电子邮件注册，它会告诉他们，并且不允许他们注册

require 'rubygems'
require 'sinatra'
require 'mysql'

get "/" do
        erb :form
end

post "/" do

begin
        con = Mysql.new('localhost', 'tut', 'tut', 'recruited_users')
        auth = con.query('SELECT school FROM users WHERE email = "#{params[:email]}" AND password = "#{params[:password]}"')
        auth.fetch_row
        ensure
                con.close if con
        end
end

get '/signup' do
        erb :signup
end

post '/signup' do

begin
        con = Mysql.new('localhost', 'tut', 'tut', 'recruited_users')
        check_for_user = con.query("SELECT email FROM users WHERE email = '#{params[:email]}'")
        if check_for_user == ''
                "Sorry, but there is already an account for this user. The ID is '#{params[:check_for_user]}', please try again"
        else
                auth = con.query("INSERT INTO users (email, password, school) VALUES('#{params[:email]}', '#{params[:password]}', '#{params[:school]}')")
                "Succesfully created user #{params[:email]}"
        end
        ensure
                con.close if con
        end
end

The problem is that the variable check_for_user is not receiving any value, at least not one that I can work with. I need to be able to set up the if statement so that they can only create a new user if the email does not already exist in the database.

问题是变量check_for_user没有收到任何值，至少没有我可以使用的值。我需要能够设置if语句，以便只有在数据库中尚不存在电子邮件时才能创建新用户。

1 个解决方案

sth = con.query('select school from users where email = ? and password = ?')
sth.execute(params[:email], params[:password])
row = sth.fetch
if(!row)
    # Didn't find anything
else
    # The school is in row.first
end