ror mysql查询语句错误

# 错误的查询语句
User.where("age > ?", 18).order("name")

# 正确的查询语句
User.where("age > ?", 18).order(name: :asc)

# 错误的查询逻辑
User.where("age > ?", 18).where("created_at < ?", Time.now)

# 正确的查询逻辑
User.where("age > ?", 18).where("created_at < ?", Time.now.beginning_of_day)

# 数据库连接配置错误
development:
  adapter: mysql2
  encoding: utf8
  database: myapp_development
  username: root
  password: 
  host: localhost

# 正确的数据库连接配置
development:
  adapter: mysql2
  encoding: utf8
  database: myapp_development
  username: root
  password: your_password
  host: localhost

# 性能较差的查询语句
User.includes(:orders).where("orders.total > ?", 100)

# 优化后的查询语句
User.joins(:orders).where("orders.total > ?", 100).select("users.*, SUM(orders.total) as total_spent").group("users.id")