update_all

Base.update_all(updates, conditions = nil, options = {})

前面为执行语句，后面为where语句。

源码

# File active_record/base.rb, line 670
def update_all(updates, conditions = nil, options = {})
  sql  = "UPDATE #{table_name} SET #{sanitize_sql_for_assignment(updates)} "
  scope = scope(:find)
  add_conditions!(sql, conditions, scope)
  add_order!(sql, options[:order], scope)
  add_limit!(sql, options, scope)
  connection.update(sql, "#{name} Update")
end

例子

# Update all billing objects with the 3 different attributes given
Billing.update_all( "category = 'authorized', approved = 1, author = 'David'" )

# Update records that match our conditions
Billing.update_all( "author = 'David'", "title LIKE '%Rails%'" )

# Update records that match our conditions but limit it to 5 ordered by date
Billing.update_all( "author = 'David'", "title LIKE '%Rails%'",
                      :order => 'created_at', :limit => 5 )