使用 sql 查询结果填充 datagridview

Question

我正在尝试显示查询结果，但我不断得到一个空白的数据网格。 好像数据本身是不可见的

这是我的代码：

 private void Employee_Report_Load(object sender, EventArgs e)
 {
     string select = "SELECT * FROM tblEmployee";
     Connection c = new Connection();
     SqlDataAdapter dataAdapter = new SqlDataAdapter(select, c.con); //c.con is the connection string
     SqlCommandBuilder commandBuilder = new SqlCommandBuilder(dataAdapter);

     DataTable table = new DataTable();
     table.Locale = System.Globalization.CultureInfo.InvariantCulture;
     dataAdapter.Fill(table);
     bindingSource1.DataSource = table;

     dataGridView1.ReadOnly = true;        
     dataGridView1.DataSource = bindingSource1;
}

这段代码有什么问题？

Answer 1

您的代码已修复。接下来忘记绑定源

 var select = "SELECT * FROM tblEmployee";
 var c = new SqlConnection(yourConnectionString); // Your Connection String here
 var dataAdapter = new SqlDataAdapter(select, c); 

 var commandBuilder = new SqlCommandBuilder(dataAdapter);
 var ds = new DataSet();
 dataAdapter.Fill(ds);
 dataGridView1.ReadOnly = true; 
 dataGridView1.DataSource = ds.Tables[0];

Answer 2

String strConnection = Properties.Settings.Default.BooksConnectionString;
SqlConnection con = new SqlConnection(strConnection);

SqlCommand sqlCmd = new SqlCommand();
sqlCmd.Connection = con;
sqlCmd.CommandType = CommandType.Text;
sqlCmd.CommandText = "Select * from titles";
SqlDataAdapter sqlDataAdap = new SqlDataAdapter(sqlCmd);

DataTable dtRecord = new DataTable();
sqlDataAdap.Fill(dtRecord);
dataGridView1.DataSource = dtRecord;

Answer 3

你不需要bindingSource1

只需设置dataGridView1.DataSource = table;

Answer 4

尝试将您的DataGridView 绑定到DataTable 的DefaultView：

dataGridView1.DataSource = table.DefaultView;

Answer 5

这应该是最安全的错误代号查询：

    public void Load_Data()
        {
            using (SqlConnection connection = new SqlConnection(DatabaseServices.connectionString)) //use your connection string here
            {
                var bindingSource = new BindingSource();
                string fetachSlidesRecentSQL = "select top (50) * from dbo.slides order by created_date desc";
                using (SqlDataAdapter dataAdapter = new SqlDataAdapter(fetachSlidesRecentSQL, connection))
                {
                    try
                    {
                       SqlCommandBuilder commandBuilder = new SqlCommandBuilder(dataAdapter);

                        DataTable table = new DataTable();
                        dataAdapter.Fill(table);
                        bindingSource.DataSource = table;
                        recent_slides_grd_view.ReadOnly = true;
                        recent_slides_grd_view.DataSource = bindingSource;
                    }
                    catch (SqlException ex)
                    {
                       MessageBox.Show(ex.Message.ToString(), "ERROR Loading");
                    }
                    finally
                    {
                        connection.Close();
                    }
                }

            }
        }

Answer 6

如果您将数据源设置为您添加到表单但未使用的数据集，您可能会得到一个空白的数据网格。如果您基于上述代码以编程方式设置数据源，请将其设置为 None。

Answer 7

您可以尝试这个示例，并始终检查您的连接字符串，您可以使用此示例，无论是否使用 bindingsource，您都可以将数据加载到 datagridview。

private void Employee_Report_Load(object sender, EventArgs e)
{
        var table = new DataTable();

        var connection = "ConnectionString";

        using (var con = new SqlConnection { ConnectionString = connection })
        {
            using (var command = new SqlCommand { Connection = con })
            {

                if (con.State == ConnectionState.Open)
                {
                    con.Close();
                }

                con.Open();

                try
                {
                    command.CommandText = @"SELECT * FROM tblEmployee";
                    table.Load(command.ExecuteReader());

                    bindingSource1.DataSource = table;

                    dataGridView1.ReadOnly = true;
                    dataGridView1.DataSource = bindingSource1;

                }
                catch(SqlException ex)
                {
                    MessageBox.Show(ex.Message + " sql query error.");
                }

            }

        }

 }

Answer 8

您必须将属性表添加到 DataGridView 数据源

 dataGridView1.DataSource = table.Tables[0];

Answer 9

如果你用的是mysql这个代码你可以使用。

string con = "SERVER=localhost; user id=root; password=; database=databasename";
    private void loaddata()
{
MySqlConnection connect = new MySqlConnection(con);
connect.Open();
try
{
MySqlCommand cmd = connect.CreateCommand();
cmd.CommandText = "SELECT * FROM DATA1";
MySqlDataAdapter da = new MySqlDataAdapter(cmd);
DataTable dt = new DataTable();
da.Fill(dt);
datagrid.DataSource = dt;
}
catch(Exception ex)
{
MessageBox.Show(ex.Message);
}
}

Answer 10

晚了几年，但这是其他人最简单的方法。

String connectionString = @"Data Source=LOCALHOST;Initial Catalog=DB;Integrated Security=true";

SqlConnection cnn = new SqlConnection(connectionString);
SqlDataAdapter sda = new SqlDataAdapter("SELECT * FROM tblEmployee;", cnn);

DataTable data = new DataTable();
sda.Fill(data);

DataGridView1.DataSource = data;

没有必要使用DataSet，DataTable 应该足够好了。 SQLCommandBuilder 也不需要。

Answer 11

我认为这是从一开始就编写的专业方式，但是您可以将此代码与 MySQL 一起使用，但我认为它们是相同的：

1/

using System.Data; AND using MySql.Data.MySqlClient;

2/

MySqlConnection con = new MySqlConnection("datasource=172.16.2.104;port=3306;server=localhost;database=DB_Name=root;password=DB_Password;sslmode=none;charset=utf8;");
        MySqlCommand cmd = new MySqlCommand();

3/

public void SetCommand(string SQL)
{
    cmd.Connection = con;
    cmd.CommandText = SQL;

}
private void FillGrid()
{
    SetCommand("SELECT * FROM `transport_db`ORDER BY `id` DESC LIMIT 15");
    DataTable tbl = new DataTable();
    tbl.Load(cmd.ExecuteReader());
    dataGridView1.DataSource = tbl;
}