如何删除数据库中最后插入的记录？ [英] How do i delete the last inserted record on database?

问题描述

你好，



我有这个SQL语法来删除最后一条记录，但似乎拒绝工作......





代码段：

Hello,

I have this SQL syntax to delete the last record, but it seems to refuse to work...


Code Snippet:

private void cmdAnular_Click(object sender, EventArgs e)
{
    string SQL = "DELETE FROM entradas WHERE id_entrada = @entrada ORDER BY id_entrada DESC LIMIT 1";

    using (var cn = new MySqlConnection("server = localhost; user id = root; password = 12345; persistsecurityinfo = True; database = portaria; allowuservariables = True"))
    {
        using (var cmd = new MySqlCommand(SQL, cn))
        {
            int i = 0;
          cmd.Parameters.Clear();
          cmd.Parameters.AddWithValue("@entrada", Grid1.Rows[i].Cells["#"].Value);
          MySqlDataAdapter sda = new MySqlDataAdapter();
          DataTable dt = new DataTable();
          sda.SelectCommand = cmd;
          sda.Fill(dt);
          Grid1.Update();
          Grid1.Refresh();

          cn.Open();
        }
        cn.Close();
        cmdAnular.Enabled = false;
    }
}

SQLyog日志：

SQLyog LOG:

1 queries executed, 1 success, 0 errors, 0 warnings

Query: DELETE FROM entradas WHERE id_entrada = @entrada ORDER BY id_entrada DESC LIMIT 1

0 row(s) affected

Execution Time : 0 sec
Transfer Time  : 0 sec
Total Time     : 0.001 sec

我尝试过：



尝试使用记录ID检查＃上显示的最高编号，然后将其删除。但是这个查询在SQLyog上没问题，但在实际程序上没有做任何事情。

What I have tried:

Tried to use record id to check the highest number shown on "#" and then delete it. But this query is fine on SQLyog, but not doing anything on the actual program.

推荐答案

You can add an auto increment/IDENTITY column, it will keep the track of inserted data. You can use the IDENTITY column in where condition of DELETE
Example:
[ID]           INT           IDENTITY (1, 1) NOT NULL

DELETE FROM Employee WHERE ID in(SELECT MAX(ID) FROM Employee) 

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