Question

mysql命令根据条件

从其他列生成列

loan_amount | installment | start_date | status       
------------------------------------------------------------------  
500         | 100         | 2018-1-1   |

if（loan_amount％installment！= 0）then month_required to pay = loan_amount / installment + 1 else month_required = loan_amount / installment;

然后我想通过将month_required添加到start_date进行检查（如果它已超过当前日期）。如果没有，则状态将生成“不完整”，否则为“完成”。

delimiter //

set @month = "0";

create trigger `status_check` before insert on `loan` 
for each row 
  begin 
    if NEW.loan_amount% NEW.installment != 0 
        then set @month NEW.loan_amount/ NEW.installment +1;
    else set @month = NEW.loan_amount/NEW.installment;

   end if ;

   if NOW() <= dateadd(NEW.start_date,INTERVAL @month MONTH) 
   then set NEW.status = "incomplete";
   else set NEW.status = "complete";
  end if;

end;
//
DELIMITER ;

这里的错误是什么？请帮忙。

Answer 1

我无法提供真正的答案，因为您没有提供所有数据库字段或数据样本，但某些BEFORE INSERT和BEFORE UPDATE触发器可能会完成这项工作。

这是BEFORE INSERT：

的基础

DELIMITER //

DROP TRIGGER IF EXISTS `trg_test_insert`;
//

CREATE TRIGGER `trg_test_insert`
BEFORE INSERT ON `table`
FOR EACH ROW
BEGIN

    IF NEW.loan_amount % NEW.installment != 0 THEN
        SET NEW.month_required = NEW.loan_amount / NEW.installment + 1;
    ELSE
        SET NEW.month_required = NEW.loan_amount / NEW.installment;
    END IF;

END;
//

DELIMITER ;

查看MySQL 5.7 Reference Manual / ... / Trigger Syntax and Examples

并在： MYSQL Triggers - how to store the result of a calculated field

用条件sql生成colunm

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