大數量查詢分頁顯示 微軟的解決辦法

微軟的解決辦法
using System; 
using System.Data; 
using System.Data.SqlClIEnt; 
using System.Drawing; 
using System.Windows.Forms;

public class PagingSample: Form 
{ 
// Form controls. 
Button prevBtn = new Button(); 
Button nextBtn = new Button();

static DataGrid myGrid = new DataGrid(); 
static Label pageLbl = new Label();

// Paging variables. 
static int pageSize = 10; // Size of vIEwed page. 
static int totalPages = 0; // Total pages. 
static int currentPage = 0; // Current page. 
static string firstVisibleCustomer = ""; // First customer on page to determine location for move previous. 
static string lastVisibleCustomer = ""; // Last customer on page to determine location for move next.

// DataSet to bind to DataGrid. 
static DataTable custTable;

// Initialize connection to database and DataAdapter. 
static SqlConnection nwindConn = new SqlConnection("Data Source=localhost;Integrated Security=SSPI;Initial Catalog=northwind"); 
static SqlDataAdapter custDA = new SqlDataAdapter("", nwindConn); 
static SqlCommand selCmd = custDA.SelectCommand;

public static void GetData(string direction) 
{ 
// Create SQL statement to return a page of records. 
selCmd.Parameters.Clear();

switch (direction) 
{ 
case "Next": 
selCmd.CommandText = "SELECT TOP " + pageSize + " CustomerID, CompanyName FROM Customers " + 
"WHERE CustomerID > @CustomerId ORDER BY CustomerID"; 
selCmd.Parameters.Add("@CustomerId", SqlDbType.VarChar, 5).Value = lastVisibleCustomer; 
break; 
case "Previous": 
selCmd.CommandText = "SELECT TOP " + pageSize + " CustomerID, CompanyName FROM Customers " + 
"WHERE CustomerID < @CustomerId ORDER BY CustomerID DESC"; 
selCmd.Parameters.Add("@CustomerId", SqlDbType.VarChar, 5).Value = firstVisibleCustomer; 
break; 
default: 
selCmd.CommandText = "SELECT TOP " + pageSize + " CustomerID, CompanyName FROM Customers ORDER BY CustomerID";

// Determine total pages. 
SqlCommand totCMD = new SqlCommand("SELECT Count(*) FROM Customers", nwindConn); 
nwindConn.Open(); 
int totalRecords = (int)totCMD.ExecuteScalar(); 
nwindConn.Close(); 
totalPages = (int)Math.Ceiling((double)totalRecords / pageSize);

break; 
}

// Fill a temporary table with query results. 
DataTable tmpTable = new DataTable("Customers"); 
int recordsAffected = custDA.Fill(tmpTable);

// If table does not exist, create it. 
if (custTable == null) 
custTable = tmpTable.Clone();

// Refresh table if at least one record returned. 
if (recordsAffected > 0) 
{ 
switch (direction) 
{ 
case "Next": 
currentPage++; 
break; 
case "Previous": 
currentPage--; 
break; 
default: 
currentPage = 1; 
break; 
}

pageLbl.Text = "Page " + currentPage + " of " + totalPages;

// Clear rows and add new results. 

custTable.Rows.Clear();

foreach (DataRow myRow in tmpTable.Rows) 
custTable.ImportRow(myRow);

// Preserve first and last primary key values. 
DataRow[] ordRows = custTable.Select("", "CustomerID ASC"); 
firstVisibleCustomer = ordRows[0][0].ToString(); 
lastVisibleCustomer = ordRows[custTable.Rows.Count - 1][0].ToString(); 
} 
}

public PagingSample() 
{ 
// Initialize controls and add to form. 
this.ClIEntSize = new Size(360, 274); 
this.Text = "NorthWind Data";

myGrid.Location = new Point(10,10); 
myGrid.Size = new Size(340, 220); 
myGrid.AllowSorting = true; 
myGrid.CaptionText = "NorthWind Customers"; 
myGrid.ReadOnly = true; 
myGrid.AllowNavigation = false; 
myGrid.PreferredColumnWidth = 150;

prevBtn.Text = "<<"; 
prevBtn.Size = new Size(48, 24); 
prevBtn.Location = new Point(92, 240); 
prevBtn.Click += new EventHandler(Prev_OnClick);

nextBtn.Text = ">>"; 
nextBtn.Size = new Size(48, 24); 
nextBtn.Location = new Point(160, 240);

pageLbl.Text = "No Records Returned."; 
pageLbl.Size = new Size(130, 16); 
pageLbl.Location = new Point(218, 244);

this.Controls.Add(myGrid); 
this.Controls.Add(prevBtn); 
this.Controls.Add(nextBtn); 
this.Controls.Add(pageLbl); 
nextBtn.Click += new EventHandler(Next_OnClick);

// Populate DataSet with first page of records and bind to grid. 
GetData("Default"); 
DataView custDV = new DataView(custTable, "", "CustomerID", DataVIEwRowState.CurrentRows); 
myGrid.SetDataBinding(custDV, ""); 
}

public static void Prev_OnClick(object sender, EventArgs args) 
{ 
GetData("Previous"); 
}

public static void Next_OnClick(object sender, EventArgs args) 
{ 
GetData("Next"); 
} 
}

public class Sample 
{ 
static void Main() 
{ 
Application.Run(new PagingSample()); 
} 
}