Question

我的代码遇到了一些奇怪的问题。在我的表中，我有58条记录，当我使用消息框运行时，我得到57作为MaxRecord，这是正确的，假设第一条记录以0开始。

当我点击Last_Button滚动到最后一条记录时，它会显示

第57位没有排。

我的代码有问题吗？感谢。

namespace ClassLibrary1
{
    public partial class myfunction : Form
    {
        public int CarNumber { get; set; }
        public kilnRec CurrentKilnRec { get; set; }
        public int CurrentIndex { get; set; }
        public int LastIndex { get; set; }
        public int MaxIndex { get; set; }
        public string CarNo { get; set; }

        public myfunction()
        {
            InitializeComponent();
        }

        private void myfunction_Shown(object sender, EventArgs e)
        {
            try
            {
                LoadDB();
                ResetButton();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.StackTrace);
                throw ex;
            }
        }

        private void myfunction_Load(object sender, EventArgs e)
        {
            LastIndex = 0;
        }

        public OleDbConnection DBConnection { get; set; }
        public DataTable mytableTable { get; set; }

        private void LoadDB()
        {
            DBConnection = new OleDbConnection(DbManager.DbConnectionString);
            DBConnection.Open();
            var oleDBCmd = new OleDbCommand("SELECT * FROM mytable WHERE rec_no >= -9 AND rec_no <= 48 ORDER BY rec_no", DBConnection)
            {
                CommandType = CommandType.Text
            };
            var oleDBDataAdapter = new OleDbDataAdapter(oleDBCmd);
            var dataset = new DataSet();
            oleDBDataAdapter.Fill(dataset);
            mytableTable = dataset.Tables[0];
            MaxIndex = dataset.Tables[0].Rows.Count;
            MessageBox.Show(Convert.ToString(MaxIndex));
            CurrentIndex = LastIndex;
            CurrentKilnRec = new kilnRec();
            SetRecord();
        }

        private void SetRecord()
        {
            var CurrentRow = mytableTable.Rows[CurrentIndex];
            this.tbCarPos.Text = Convert.ToString(CurrentRow["rec_no"]);
            this.tbCarNumber.Text = Convert.ToString(CurrentRow["carno"]);
            this.tbProdName.Text = Convert.ToString(CurrentRow["prodname"]);
            this.tbQuantity.Text = Convert.ToString(CurrentRow["quantity"]);
            this.tbWeight.Text = Convert.ToString(CurrentRow["weight"]);
        }

        private void ResetButton()
        {
            bt_First.Enabled = true;
            bt_Prior.Enabled = true;
            bt_Next.Enabled = true;
            bt_Last.Enabled = true;

            if (CurrentIndex == 0)
            {
                bt_First.Enabled = false;
                bt_Prior.Enabled = false;
                bt_Next.Enabled = true;
                bt_Last.Enabled = true;
            }

            if (CurrentIndex == MaxIndex)
            {
                bt_First.Enabled = true;
                bt_Prior.Enabled = true;
                bt_Next.Enabled = false;
                bt_Last.Enabled = false;
            }
        }

        private void bt_First_Click(object sender, EventArgs e)
        {
            CurrentIndex = 0;
            SetRecord();
            ResetButton();
        }

        private void bt_Prior_Click(object sender, EventArgs e)
        {
            CurrentIndex--;
            SetRecord();
            ResetButton();
        }

        private void bt_Next_Click(object sender, EventArgs e)
        {
            CurrentIndex++;
            SetRecord();
            ResetButton();
        }

        private void bt_Last_Click(object sender, EventArgs e)
        {
            CurrentIndex = MaxIndex;
            SetRecord();
            ResetButton();
        }
    }
}

Answer 1

您的MaxIndex是项目（行）的总数。从0开始，此索引可以达到MaxIndex - 1。

如果MaxIndex为57，则索引为0到56（总计为57）。

因此，在您的代码中，使用MaxIndex-1转到最后一项/行，使用相同的CurrentIndex == MaxIndex-1启用“第一个”按钮。

C＃：位置没有排

1 个答案: