连接数据库是access
语句是这样的
string sql = " SELECT productID as CIQ产品编号," +
" productName as CIQ产品名称 from T_P_Product where productID not in( select categoryID from T_P_Product)";
string strConnectionString = ORMapping.Accesslayer.DataProvider.DataProviderFactory.createInstance().getNewConnection().ConnectionString;
OleDbConnection oleConn = new OleDbConnection(strConnectionString);
oleConn.Open();
DataSet ds = new DataSet();
OleDbDataAdapter da = new OleDbDataAdapter();
da.SelectCommand = new OleDbCommand(sql, oleConn); ds.EnforceConstraints = false;
da.Fill(ds,"List");
ds.EnforceConstraints = true;
把查询的结构赋值到一个DataGrid,弹出含有这个DataGrid的窗体,结果要等1分多,而用SQLServer就很快,谁有办法解决这个问题.
语句是这样的
string sql = " SELECT productID as CIQ产品编号," +
" productName as CIQ产品名称 from T_P_Product where productID not in( select categoryID from T_P_Product)";
string strConnectionString = ORMapping.Accesslayer.DataProvider.DataProviderFactory.createInstance().getNewConnection().ConnectionString;
OleDbConnection oleConn = new OleDbConnection(strConnectionString);
oleConn.Open();
DataSet ds = new DataSet();
OleDbDataAdapter da = new OleDbDataAdapter();
da.SelectCommand = new OleDbCommand(sql, oleConn); ds.EnforceConstraints = false;
da.Fill(ds,"List");
ds.EnforceConstraints = true;
把查询的结构赋值到一个DataGrid,弹出含有这个DataGrid的窗体,结果要等1分多,而用SQLServer就很快,谁有办法解决这个问题.
解决方案 »
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查询结果分页是以较小数据子集(即页)的形式返回查询结果的过程。它通常用于以易于管理的小块区的形式向用户显示结果。DataAdapter 提供了通过 Fill 方法的重载来仅返回一页数据的功能。但是,对于大量的查询结果,它可能并不是首选的分页方法,因为 DataAdapter 虽然仅使用所请求的记录来填充目标 DataTable 或 DataSet,但仍会使用返回整个查询的资源。若要在从数据源中返回一页数据时不使用返回整个查询所需的资源,请为查询指定附加条件,使返回的行数减少到只返回所需的行。若要使用 Fill 方法返回一页数据,请指定 startRecord(它指定该数据页的第一个记录),并指定 maxRecords(它指定该数据页中的记录数)。以下代码示例显示如何使用 Fill 方法来返回查询结果(页大小为 5 个记录)的第一页。int currentIndex = 0;
int pageSize = 5;string orderSQL = "SELECT * FROM Orders ORDER BY OrderID";
SqlDataAdapter myDA = new SqlDataAdapter(orderSQL, nwindConn);DataSet myDS = new DataSet();
myDA.Fill(myDS, currentIndex, pageSize, "Orders");在上例中,DataSet 只填充了 5 个记录,但却返回了整个 Orders 表。若要用相同的 5 个记录填充 DataSet 但仅返回这 5 个记录,请在 SQL 语句中使用 TOP 和 WHERE 语句,如以下代码示例所示。int pageSize = 5;string orderSQL = "SELECT TOP " + pageSize + " * FROM Orders ORDER BY OrderID";
SqlDataAdapter myDA = new SqlDataAdapter(orderSQL, nwindConn);DataSet myDS = new DataSet();
myDA.Fill(myDS, "Orders");请注意,当以这种方式进行查询结果分页时,将需要保留用作行排序依据的唯一标识符,以便将唯一的 ID 传递给用于返回下一页记录的命令,如以下代码示例所示。string lastRecord = myDS.Tables["Orders"].Rows[pageSize - 1]["OrderID"].ToString();若要使用附带 startRecord 和 maxRecords 参数的 Fill 方法的重载来返回下一页记录,请使当前记录索引按页大小递增,并填充该表。请记住,即使仅在 DataSet 中添加一页记录,数据库服务器仍会返回全部查询结果。在以下代码示例中,先清除表行,然后再用下一页数据填充这些表行。您可能需要在本地缓存中保留一定数量的返回行,以减少到数据库服务器的往返过程。currentIndex += pageSize;myDS.Tables["Orders"].Rows.Clear();myDA.Fill(myDS, currentIndex, pageSize, "Orders");若要返回下一页记录而不让数据库服务器返回整个查询,请指定对 SQL SELECT 语句的限制条件。由于上例保留了返回的最后一个记录,因此可以在 WHERE 子句中使用它来指定查询的起点,如以下代码示例所示。orderSQL = "SELECT TOP " + pageSize + " * FROM Orders WHERE OrderID > " + lastRecord + " ORDER BY OrderID";
myDA.SelectCommand.CommandText = orderSQL;myDS.Tables["Orders"].Rows.Clear();myDA.Fill(myDS, "Orders");下面是一个查询结果分页的示例,它在 SQL 语句中指定特定条件,以便一次仅从数据库中返回一页记录。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());
}
}
SELECT productID as CIQ产品编号, productName as CIQ产品名称 from T_P_Product where productID not in( select distinct categoryID from T_P_Product)
http://dotnet.aspx.cc/ShowDetail.aspx?id=47DD34FD-ED0B-4455-94E8-CD9F63E19893
magma(澎湃) ( )的方法是一个临时应急的方法