Question

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.OleDb;


namespace testdb
{
    public partial class Form1 : Form
    {
        private string constr =
            @"Provider = Microsoft.ACE.OLEDB.12.0; Data Source =     C:/Users/Xprts_3/Documents/Database1.accdb";

        public Form1()
        {
            InitializeComponent();
            Bind();
        }

        private void Bind()
        {
            OleDbConnection con = new OleDbConnection(constr);
            OleDbCommand cmd = new OleDbCommand();

            cmd.Connection = con;
            cmd.CommandText = "select * from tb1";
            cmd.CommandType = CommandType.Text;
            OleDbDataAdapter da = new OleDbDataAdapter();
            da.SelectCommand = cmd;
            DataSet ds = new DataSet();
            da.Fill(ds);
            dataGridView1.DataSource = ds.Tables[0];
            for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
            {
                dataGridView1.Rows.Add(new DataGridViewRow());
                int j;
                for (j = 0; j < ds.Tables[0].Columns.Count; j++)
                {
                    dataGridView1.Rows[i].Cells[j].Value = ds.Tables[0].Rows[i][j].ToString();
                }
            }

            con.Close();
        }
    }
}

这是我在DataGridView中从数据库中获取数据的代码，但它显示此错误：

当控件受数据绑定时，无法以编程方式将行添加到DataGridView的行集合中在这一行：

dataGridView1.Rows.Add(new DataGridViewRow());

Answer 1

更新回答：

首先，您应该将对数据库的调用与其余代码分开。让我们创建一个负责良好的GetData()方法......获取数据：）

private DataSet GetData(string constr) {
    //'using' constructs are always a good idea when dealing with database operations
    //your connection will automatically close
    using(OleDbConnection con = new OleDbConnection(constr)){
        using(OleDbCommand cmd = new OleDbCommand()){       
            cmd.Connection = con;
            cmd.CommandText = "select * from tb1";
            cmd.CommandType = CommandType.Text;
            OleDbDataAdapter da = new OleDbDataAdapter();
            da.SelectCommand = cmd;
            DataSet ds = new DataSet();
            da.Fill(ds);
            return ds;
        }
    }
}

然后要绑定DataGridView，您有两个选择：

使用DataBind()方法
以编程方式创建网格列和行

方法1 - DataBind（）方式：

private void BindWithDataBind() {
    dataGridView1.DataSource = GetData();
    //call the databind method to bound the data to the grid
    //the grid structure will be created automatically from the datatable structure
    dataGridView1.DataBind(); 
}

方法2 - 编程方式

private void BindProgramatically() {

    //obtain the data from your OleDB connection
    DataSet ds = GetData(constr);
    if(ds == null) {
        return;
    }
    DataTable dt = ds.Tables[0];

    //build the grid structure, add a new grid column for each datatable column
    for(int i = 0; i < dt.Columns.Count; i++) {
        DataGridViewColumn newColumn = new DataGridViewColumn();
        newColumn.Name = dt.Columns[i].ColumnName;
        dataGridView1.Columns.Add(newColumn);
    }   

    for (int i = 0; i < dt.Rows.Count; i++) {
        //call ToArray to pass a copy of the data from the datatable
        //(make sure you have 'using System.Linq;' at the top of your file
        dataGridView1.Rows.Add(dt.Rows[i].ItemArray.ToArray());
    }
}

在MSDN关于DataGridView.Columns属性的官方文档中，您可以通过编程方式找到有关绑定的更多信息。这是link。

Answer 2

Lucian的答案是对的，你应该在这种情况下使用DataBind（）。但是如果你想以另一种方式在DataGridView中添加行，这里有一个示例：

private void Bind()
{
    OleDbConnection con = new OleDbConnection(constr);
    OleDbCommand cmd = new OleDbCommand();

    cmd.Connection = con;
    cmd.CommandText = "select * from tb1";
    cmd.CommandType = CommandType.Text;
    OleDbDataAdapter da = new OleDbDataAdapter();
    da.SelectCommand = cmd;
    DataSet ds = new DataSet();
    da.Fill(ds);


    for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
    {
        var row = (DataGridViewRow)dataGridView1.Rows[0].Clone();

        for (int j = 0; j < ds.Tables[0].Columns.Count; j++)
        {
            row.Cells[j].Value = ds.Tables[0].Rows[i][j].ToString();
        }

        dataGridView1.Rows.Add(row);
    }

    con.Close();
}

未经测试，但我认为它应该可行。只是评论结果。

在C＃中的datagridview中获取数据

2 个答案: