adpater.update（）问题，insert没问题，update就报错 affected 0 of the expected 1 records

2009-11-11 10:55:35 406 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

PostgreSQL merge insert(upsert/insert into on conflict) 如何区分数据是INSERT还是UPDATE 背景使用insert into on conflict update语法，可以支持UPSERT的功能，但是到底这条SQL是插入的还是更新的呢？如何判断通过xmax字段的值是否不为0，可以判断，如果是UPDATE，XMAX里面会填充更新事务号。注意直接用UPDATE语句更新的话，XMAX会写入0，因为是新版本，而老版本上XMAX会填入更新事务号。例子... 阅读详情

窗口只有1个datagridview和一个button1，datagidview编辑数据，button1确定更新
当插入新数据的时候，可以成功插入，当编辑现有数据update的时候，一点更新就报错。提示：“Concurrency violation: the DeleteCommand affected 0 of the expected 1 records.”
我根本不知道错在哪里了。希望指点

代码如下



    public partial class FormAccess : Form

    {

        OleDbConnection connect = new OleDbConnection(@";Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\ESDB.accdb");

        DataTable dt=new DataTable ();

        OleDbDataAdapter adapter;

        public FormAccess()

        {

            InitializeComponent();

        }



        private void FormAccess_Load(object sender, EventArgs e)

        {

            connect.Open();

            adapter = new OleDbDataAdapter();

            string selectText = "select * from factory";

            DbCommand selectCommand = new OleDbCommand(selectText, connect);            

            adapter.SelectCommand =(OleDbCommand ) selectCommand;

            adapter.Fill(dt);

            dataGridView1.DataSource = dt;

            string insertText="insert into factory (factoryCode,factoryName,description) values(@factoryCode,@factoryName,@description)";

            string updateText = "update factory set factoryName=@factoryname,description=@description where factoryCode=@factoryCode";

            OleDbCommand insertCommand = new OleDbCommand(insertText, connect);

            insertCommand.Parameters.Add("@factoryCode", OleDbType.VarWChar, 0, "factoryCode");

            insertCommand.Parameters.Add("@factoryName", OleDbType.VarWChar, 0, "factoryName");

            insertCommand.Parameters.Add("@description", OleDbType.VarWChar, 0, "description");



            OleDbCommand updateCommand = new OleDbCommand(updateText, connect);

            updateCommand.Parameters.Add("@factoryCode", OleDbType.VarWChar, 0, "factoryCode");

            updateCommand.Parameters.Add("@factoryName", OleDbType.VarWChar, 0, "factoryName");

            updateCommand.Parameters.Add("@description", OleDbType.VarWChar, 0, "description");



            adapter.UpdateCommand = (OleDbCommand)updateCommand;

            adapter.InsertCommand = (OleDbCommand)insertCommand;

        }



        private void button1_Click(object sender, EventArgs e)

        {

            adapter.Update(dt);

        }