MySql 和插入最后一个 ID 问题仍然存在

Question

好的，经过大量阅读和尝试，我似乎仍然无法让它工作：

      OdbcCommand cmd = new OdbcCommand("INSERT INTO User (Email) VALUES ('rusty@msn.com'); SELECT LAST_INSERT_ID();", cn);

cmd.ExecuteNonQuery();
                using (OdbcDataReader reader = cmd.ExecuteReader())
                {

                string theUserId = String.Format("{0}", reader.GetString(0));
                Label10.Text = theUserId;

表格：

User
--------
UserID (auto increment, pk)
Email

在调试模式下运行我在这一行得到错误，

            using (OdbcDataReader reader = cmd.ExecuteReader())

和，

cmd.ExecuteNonQuery();

Mysql 在这一行说它是一个语法错误SELECT LAST_INSERT_ID();", cn);但据我所知，这是合法的。

确切的错误：

ERROR [42000] [MySQL][ODBC 3.51 Driver][mysqld-5.5.9]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 'SELECT LAST_INSERT_ID()' at line 1

编辑：贾斯汀方法：

using (OdbcConnection connection = new OdbcConnection("Driver={MySQL ODBC 3.51 Driver}; Server=localhost; Database=gymwebsite2; User=root; Password=commando;"))
{
    // ODBC command and transaction objects
    OdbcCommand command = new OdbcCommand();
    OdbcTransaction transaction = null;

    // tell the command to use our connection
    command.Connection = connection;

    try
    {
        // open the connection
        connection.Open();

        // start the transaction
        transaction = connection.BeginTransaction();

        // Assign transaction object for a pending local transaction.
        command.Connection = connection;
        command.Transaction = transaction;

        // TODO: Build a SQL INSERT statement
        OdbcCommand cmd = new OdbcCommand("INSERT INTO User (Email, FirstName, SecondName, DOB, Location, Aboutme, username, password) VALUES ('" + TextBox1.Text + "', '" + TextBox2.Text + "', '" + TextBox3.Text + "', '" + TextBox4.Text + "', '" + TextBox5.Text + "', '" + TextBox6.Text + "', '" + TextBox7.Text + "', '" + TextBox8.Text + "')", connection); 

        // run the insert using a non query call
        command.CommandText = cmd.ToString();
        command.ExecuteNonQuery();

        /* now we want to make a second call to MYSQL to get the new index 
           value it created for the primary key.  This is called using scalar so it will
            return the value of the SQL  statement.  We convert that to an int for later use.*/
        command.CommandText = "select last_insert_id();";
        id = Convert.ToInt32(command.ExecuteScalar());

        // the name id doesnt not exist in the current context

        // Commit the transaction.
        transaction.Commit();
    }
    catch (Exception ex)
    {
        Label10.Text = ": " + ex.Message;

        try
        {
            // Attempt to roll back the transaction.
            transaction.Rollback();
        }
        catch
        {
            // Do nothing here; transaction is not active.
        }
    }
}

Answer 1

解决方法：

1. 在查询中添加输出参数：
2. 在查询中使用 SET @OpParam = SELECT LAST_INSERT_ID();
3. 在您的代码中获取它，就像 ((int)@OpParam.Value > 0){ pull out }。
4. 另外，如果运行 select 然后代替 NonQuery，请使用 ExecuteScalar()。

希望对你有帮助。

Answer 2

澄清，mySQL .net ODBC 驱动程序不允许像您描述的那样运行多个命令。您必须进行两个单独的调用并将它们包装在一个事务中。

// open a new connection using a default connection string I have defined elsewhere
using( OdbcConnection connection = new OdbcConnection( s_connectionString ) )
{
      // ODBC command and transaction objects
      OdbcCommand command = new OdbcCommand();
      OdbcTransaction transaction = null;

      // tell the command to use our connection
      command.Connection = connection;

      try
      {
           // open the connection
           connection.Open();

           // start the transaction
           transaction = connection.BeginTransaction();

           // Assign transaction object for a pending local transaction.
           command.Connection = connection;
           command.Transaction = transaction;

           // TODO: Build a SQL INSERT statement
           StringBuilder SQL = new StringBuilder();

           // run the insert using a non query call
           command.CommandText = SQL.ToString();
           command.ExecuteNonQuery();

           /* now we want to make a second call to MYSQL to get the new index 
              value it created for the primary key.  This is called using scalar so it will
               return the value of the SQL  statement.  We convert that to an int for later use.*/
           command.CommandText = "select last_insert_id();";
           id = Convert.ToInt32( command.ExecuteScalar() );

           // Commit the transaction.
           transaction.Commit();
     }
     catch( Exception ex )
     {
          Debug.WriteLine( ex.Message );

          try
          {
               // Attempt to roll back the transaction.
               transaction.Rollback();
            }
            catch
            {
                 // Do nothing here; transaction is not active.
              }
         }
}

Answer 3

如果您的电子邮件是唯一的，您可以使用

Select ID From User where Email='rusty@msn.com'

你确信你总是能得到正确的答案。

如果您的电子邮件不是唯一的，您应该使用锁定来确保只有在线程上执行查询，然后在插入后使用此查询

Select Max(ID) From User