C# Can'；t使用ADO.NET建立与SQL Server的连接

我正在尝试使用以下代码建立与本地SQL server的连接：

dataGridView1.Visible = true;
        SqlConnection con = new SqlConnection();
        con.ConnectionString = @"Data Source=.;Initial Catalog=Form;Integrated Security=True";
        SqlCommand com = new SqlCommand("select * from Form", con);
        SqlDataAdapter sda = new SqlDataAdapter(com);
        dataGridView1.DataSource = sda;

---

但是当我按下表单中的按钮时，它不会显示数据！我做错了什么？

您需要使用

con.open（）打开连接

此外，您还遇到了许多其他问题，如不处理资源，这可能导致内存泄漏和未关闭连接，以及未填充适配器。下面是做这件事的最佳方法

using(SqlConnection con = new SqlConnection(@"Data Source=.;Initial Catalog=Form;Integrated Security=True";))
{          

    con.Open();
    SqlCommand com = new SqlCommand("select * from Form", con);
    using(SqlDataAdapter sda = new SqlDataAdapter(com));
    {
        DataTable resultTbl = new DataTable();
        sda.Fill(resultTbl);
        dataGridView1.DataSource = resultTbl;
        dataGridView1.DataBind();
    }
}

你需要这样的东西

dataGridView1.Visible = true;
        SqlConnection con = new SqlConnection();
        con.ConnectionString = @"Data Source=.;Initial Catalog=Form;Integrated Security=True";
        con.Open()
        SqlCommand com = new SqlCommand("select * from Form", con);
        SqlDataAdapter sda = new SqlDataAdapter(com);
        DataTable dt=new DataTable();
        sda.Fill(dt);   

        dataGridView1.DataSource = dt;//set it to datatable
        dataGridView1.DataBind();

它没有给我一个错误，它只是显示dataGridView为空！你检查过表中是否有数据吗？@derloopkat是的，数据库正常并且有数据。这很有效！谢谢。请单击左侧的勾号，将其标记为正确
dataGridView1.Visible = true;
        SqlConnection con = new SqlConnection();
        con.ConnectionString = @"Data Source=.;Initial Catalog=Form;Integrated Security=True";
        con.Open()
        SqlCommand com = new SqlCommand("select * from Form", con);
        SqlDataAdapter sda = new SqlDataAdapter(com);
        DataTable dt=new DataTable();
        sda.Fill(dt);   

        dataGridView1.DataSource = dt;//set it to datatable
        dataGridView1.DataBind();