Question

我在Heredoc中有这个简单的SQL

sql = <<-SQL
  SELECT SUM(price) as total_price, 
    SUM(distance) as total_distance, 
    TO_CHAR(date, 'YYYY-MM') as month
  FROM Rides
  WHERE user_id = #{current_user.id}
  GROUP_BY month
SQL

和一个find_by_sql(sql)通话

Ride.find_by_sql(sql).each do |row|
  "#{row.month}: { total_distance: #{row.total_distance}, total_price: #{row.total_price} }" 
end

并引发错误：

ActiveRecord::StatementInvalid: PG::SyntaxError: ERROR:  syntax error at or near "GROUP_BY"
LINE 6:         GROUP_BY month
                ^
:         SELECT SUM(price) as total_price, 
          SUM(distance) as total_distance, 
          TO_CHAR(date, 'YYYY-MM') as month
        FROM Rides
        WHERE user_id = 1
        GROUP_BY month

如您所见，它可以很好地插值user_id，因此问题不在插值中。

如果我将此SQL作为字符串分配给变量，则可以正常工作，

str = "select sum(distance) as total_distance, sum(price) as total_price, to_char(date, 'YYYY-MM') as month from rides where user_id = #{ current_user.id } group by month"

heredoc有什么问题？

Answer 1

SQL有一个GROUP BY子句，而不是GROUP_BY。

sql = <<-SQL
  SELECT SUM(price) as total_price, 
    SUM(distance) as total_distance, 
    TO_CHAR(date, 'YYYY-MM') as month
  FROM Rides
  WHERE user_id = #{current_user.id}
  GROUP BY month
SQL

Rails-带Heredoc的find_by_sql引发错误

1 个答案: