如果超过3天如何从mysql中删除数据？ [英] How to delete data from mysql if more than 3 days?

问题描述

string constr = @"Data Source=192.168.*.**; Database=wsditsupport; User ID=****; Password=*****";
            using (MySqlConnection con = new MySqlConnection(constr))
            {
                using (MySqlCommand cmd = new MySqlCommand("SELECT Date_Down FROM datalogin WHERE Date_Down < Date_Down(CURDATE(), INTERVAL 3 DAY"))
                {
                    using (MySqlDataAdapter sda = new MySqlDataAdapter())
                    {
                        cmd.Connection = con;
                        sda.SelectCommand = cmd;
                        if ((DateTime.Now - cmd).Days >= 3)
                        {
                            // Delete from database
                        }
                    }
                }

我尝试过：



此代码是我的第一次尝试，但我需要帮助吗？



我需要帮助来自你们。 if（（DateTime.Now - cmd）.Days> = 3）<<<在这一行我得到错误运算符' - '不能应用于'DateTime'和'MySqlCommand'类型的操作数。那么如何解决呢？

What I have tried:

This Code are my 1st try, but I need help?

I Need Help From you guys. if ((DateTime.Now - cmd).Days >= 3) <<< at this line I'm getting error Operator '-' cannot be applied to operands of type 'DateTime' and 'MySqlCommand'. So how to fix it?

推荐答案

试试

try

select * from datalogin  as mytable where datediff(now(), mytable.date) > 3

在确定要删除的记录的同时让MySQL进行删除

Just get MySQL to do the deletion at the same time as identifying the records to delete

string constr = @"Data Source=192.168.*.**; Database=wsditsupport; User ID=****; Password=*****";
using (MySqlConnection con = new MySqlConnection(constr))
{
     using (MySqlCommand cmd = new MySqlCommand("delete from datalogin where datediff(now(), datedown) > 3;",con)
     {
          cmd.ExecuteNonQuery();            
     }
     con.Close();
}

这篇关于如果超过3天如何从mysql中删除数据？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！