使用c＃进行MySQL数据库连接 [英] MySQL database connectivity using c#

问题描述

嗨..

我用c＃连接到mysql。我想获得最后一次插入的id。我想在下次运行应用程序时使用最后插入的id + 1 ..

但每当我运行我的应用程序时，每次都得到id ...

谢谢..

Hi..
I m Connecting to mysql using c#.I want to get last inserted id.I want to use that last inserted id+1 when next time i will run application..
But whenever i will run my application get id 1 everytime..
Thanks..

推荐答案

这是当ID为自动递增时，从数据库表中获取最后一个插入的id。

This is to get the last inserted id from the database table when the ID is Auto-increment.

string InsertedId = "";
RowAffected = cmd.ExecuteCommand();

//After inserting the record you call this function to get the last inserted id from the table.
string query="SELECT LAST_INSERT_ID() FROM studinfo";
if (RowAffected > 0)
       cmd= new MySqlCommand(query, Con);
       InsertedId = cmd.ExecuteScalar();

这是另一种从表中获取lastinserted的方法。

This is another way to get the lastinserted from the table.

string filename = txtImage.Text;
        byte[] imagedata;
        fs = new FileStream(filename, FileMode.Open, FileAccess.Read);
        br = new BinaryReader(fs);
        imagedata = br.ReadBytes((int)fs.Length);
        br.Close();
        fs.Close();

        string query = "SELECT max(ID) FROM studinfo";
        cmd = new MySqlCommand(query, con);
        InsertedId = cmd.ExecuteScalar();
        //When the first time executes InsertedId will be null or empty since there wont be any records stored in the table
        if (InsertedId == "")
        {
            //Assign default value as 1.
            //then pass it as parameters
            InsertedId = 1;
        }
        else
        {
            //it will return the last inserted id you make it plus 1 so that it will get increment to get a new id.
            //then pass it as parameters
            InsertedId = InsertedId + 1;
        }

        string cmdText = "Insert into studinfo values(@ID,@First,@Last,@address,@Image)";
        cmd = new MySqlCommand(cmdText, con);
        cmd.Parameters.AddWithValue("@ID", Convert.ToInt32(InsertedId));
        cmd.Parameters.AddWithValue("@First", txtFirstName.Text);
        cmd.Parameters.AddWithValue("@Last", txtLastName.Text);
        cmd.Parameters.AddWithValue("@address", txtAddress.Text);
        cmd.Parameters.AddWithValue("@Image", imagedata);
        int rowaffected = cmd.ExecuteNonQuery();
        //string query = "SELECT LAST_INSERT_ID() FROM studinfo";
        if (rowaffected > 0)
        {
            MessageBox.Show("Inserted sucessfully");
            Clear();
            txtFirstName.Focus();
        }

希望这会对你有所帮助。

Hope this helps you.

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