看了刘振岩先生编著的《基于.NET的Web程序设计》,摘录简易数据库查询系统的实现代码。具体功能是:用户
可以选取SQL Server数据库服务器的某个数据库中的某个数据表(通过两个DropDownList控件),然后将此数据表中的所有数据显示出来(通过DataGrid控件)。
amespace accessDataBase
{
///
}
protected void DropDownList1_content()
{
myConnection=new SqlConnection("server=ZHB//SQLSERVER;User ID=sa;Pwd=sa;database=master");
myConnection.Open();
strSQL="select name from sysdatabases where dbid>=5 order by dbid desc";
myCommand=new SqlDataAdapter(strSQL,myConnection);
myCommand.Fill(ds,"database");
DropDownList1.DataSource=ds.Tables["database"].DefaultView;
DropDownList1.DataValueField=ds.Tables["database"].Columns[0].ColumnName;
DropDownList1.DataTextField=ds.Tables["database"].Columns[0].ColumnName;
DropDownList1.DataBind();
}
protected void DropDownList2_content()
{
myConnection=new SqlConnection("server=ZHB//SQLSERVER;User ID=sa;Pwd=sa;database="+DropDownList1.SelectedItem.Value.ToString()+"");
myConnection.Open();
strSQL="select name from sysobjects where xtype='u' order by crdate desc";
myCommand=new SqlDataAdapter(strSQL,myConnection);
myCommand.Fill(ds,"datatable");
if(ds.Tables["datatable"].Rows.Count!=0)
{
DropDownList2.Visible=true;
DropDownList2.DataSource=ds.Tables["datatable"].DefaultView;
DropDownList2.DataValueField=ds.Tables["datatable"].Columns[0].ColumnName;
DropDownList2.DataTextField=ds.Tables["datatable"].Columns[0].ColumnName;
DropDownList2.DataBind();
}
else
{
DropDownList2.Visible=false;
Label1.Text=DropDownList1.SelectedItem.Value+"数据库中无用户数据表!";
}
}
protected void DataGrid1_content()
{
myConnection=new SqlConnection("server=ZHB//SQLSERVER;User ID=sa;Pwd=sa;database="+DropDownList1.SelectedItem.Value.ToString()+"");
myConnection.Open();
strSQL="select * from "+DropDownList2.SelectedItem.Value.ToString();
myCommand=new SqlDataAdapter(strSQL,myConnection);
myCommand.Fill(ds,"data");
Label1.Text=DropDownList1.SelectedItem.Value+"数据库中的数据表"+DropDownList2.SelectedItem.Value;
if(ds.Tables["data"].Rows.Count!=0)
{
Label1.Text+="所有数据如下:";
DataGrid1.Visible=true;
DataGrid1.DataSource=ds.Tables["data"].DefaultView;
DataGrid1.DataBind();
}
else
{
DataGrid1.Visible=false;
Label1.Text="无数据!";
}
}
#region Web 窗体设计器生成的代码
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
//
InitializeComponent();
base.OnInit(e);
}
///
}
#endregion
private void DropDownList1_SelectedIndexChanged(object sender, System.EventArgs e)
{
DropDownList2_content();
if(ds.Tables["datatable"].Rows.Count!=0)
{
DataGrid1_content();
}
else
{
Label1.Text=DropDownList1.SelectedItem.Value+"数据库中无用户数据表!";
}
}
private void DropDownList2_SelectedIndexChanged(object sender, System.EventArgs e)
{
DataGrid1_content();
}
}
}