軌道4：MySQL的2錯誤

Question

我已經升級我的項目到Rails 4，但MySQL是有錯誤：

Mysql2::Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '=> nil OR delete_by < 1)) ORDER BY t_dest_boards . ID ASC LIMIT 1' at line 1: SELECT t_dest_boards .* FROM t_dest_boards WHERE (m_section_id = 1 AND v_employee_id = '02001' AND registration_date = '2017-02-13' AND (delete_by => nil OR delete_by < 1)) ORDER BY t_dest_boards . ID ASC LIMIT 1

在這行代碼：

tdest_tmp = TDestBoard.where("m_section_id = ? AND v_employee_id = ? AND registration_date = ? AND (delete_by => nil OR delete_by < ?)", primary_section.m_section_id, params[:id], params[:tdaily_dates]["#{id}"], 1).first

可能是什麼的正確方法在Rails 4中這樣做？提前致謝！

Answer 1

delete_by => nil可能是引發錯誤的代碼。如果你想檢查一個字段是否爲零，則在條件中使用'IS NULL'。所以更改您的代碼如下

tdest_tmp = TDestBoard.where("m_section_id = ? AND v_employee_id = ? AND registration_date = ? AND (delete_by IS NULL OR delete_by < ?)", primary_section.m_section_id, params[:id], params[:tdaily_dates]["#{id}"], 1).first 

tdest_tmp = TDestBoard.where("m_section_id = ? AND v_employee_id = ? AND registration_date = ? AND (delete_by IS NULL OR delete_by < ?)", primary_section.m_section_id, params[:id], params[:tdaily_dates]["#{id}"], 1).first