Asp.net—查询数据库中记录

Asp.net—查询数据库中记录

查询数据库中记录

查询数据库中记录时,首先创建SqlConnection对象连接数据库,然后定义查询字符串,最后对GridView控件进行数据绑定。

示例:

查询数据库中记录

下面通过一个示例介绍在ASP.NET 2.0应用程序中如何查询数据库中记录。新建一个网站,默认主页为Default.aspx,在Default.aspx页面上分别添加一个TextBox控件、一个Button控件和一个GridView控件,并把Button控件的Text属性值设为“查询”。

该页在实现时,首先编写一个GridView控件数据绑定方法bind(该方法请参见5.3.2中bind方法),并在Page_Load事件中调用该方法显示数据库中记录,具体代码如下。

   protected void Page_Load(object sender, EventArgs e)

    {

        if (!IsPostBack)

        {

            this.bind();

        }

    }

然后在【查询】按钮Click事件下编写实现数据库查询操作的代码,具体代码如下。

protected void Button1_Click(object sender, EventArgs e)

    {

        if (TextBox1.Text != "")

        {

            string str = "select * from Region where RegionID='" + TextBox1.Text.Trim() + "'";

            sqlconn = new SqlConnection(sqlstr);

            sqlconn.Open();

            SqlCommand sqlcom = new SqlCommand(str,sqlconn);

            int result = Convert.ToInt32(sqlcom.ExecuteScalar());

            if (result > 0)

            {

                SqlDataAdapter myda = new SqlDataAdapter(str, sqlconn);

                DataSet myds = new DataSet();

                myda.Fill(myds);

                GridView1.DataSource = myds;

                GridView1.DataBind();

                sqlconn.Close();

            }

            else

                Response.Write("");

        }

        else

            this.bind();

    }

执行程序,示例运行结果如图1所示。

图1查询数据库中记录

程序完整代码如下:

★★★★★Default.aspx.cs代码文件★★★★★

using System;

using System.Data;

using System.Configuration;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.Data.SqlClient;

public partial class _Default : System.Web.UI.Page

{

    string sqlstr = "Data Source=(local);Database=Northwind;Uid=sa;Pwd=";

    SqlConnection sqlconn;

    protected void Page_Load(object sender, EventArgs e)

    {

        if (!IsPostBack)

        {

            this.bind();

        }

    }

    protected void Button1_Click(object sender, EventArgs e)

   {

        if (TextBox1.Text != "")

        {

            string str = "select * from Region where RegionID='" + TextBox1.Text.Trim() + "'";

            sqlconn = new SqlConnection(sqlstr);

            sqlconn.Open();

            SqlCommand sqlcom = new SqlCommand(str,sqlconn);

            int result = Convert.ToInt32(sqlcom.ExecuteScalar());

            if (result > 0)

            {

                SqlDataAdapter myda = new SqlDataAdapter(str, sqlconn);

                DataSet myds = new DataSet();

                myda.Fill(myds);

                GridView1.DataSource = myds;

                GridView1.DataBind();

                sqlconn.Close();

            }

            else

                Response.Write("");

        }

        else

            this.bind();

    }

    public void bind()

    {

        string str = "select * from Region";

        sqlconn = new SqlConnection(sqlstr);

        sqlconn.Open();

        SqlDataAdapter myda = new SqlDataAdapter(str, sqlconn);

        DataSet myds = new DataSet();

        myda.Fill(myds);

        GridView1.DataSource = myds;

        GridView1.DataBind();

        sqlconn.Close();

    }

}

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