極限記錄

Question

我有這個功能從數據庫中顯示記錄到FlowLayoutPanel的

flowLayoutPanel1.Controls.Clear(); 
     using (SqlConnection myDatabaseConnection = new SqlConnection(myConnectionString.ConnectionString)) 
     { 
      myDatabaseConnection.Open(); 
      string a = "Select EmpID, Name from EmpTable"; 
      using (SqlCommand SqlCommand = new SqlCommand(" "+ a +" ", myDatabaseConnection)) 
      { 
       int i = 0; 
       SqlDataReader DR1 = SqlCommand.ExecuteReader(); 
       while (DR1.Read()) 
       { 
        i++; 
        BookUserControl usercontrol = new BookUserControl(); 
        usercontrol.Tag = i; 
        usercontrol.EmpID = DR1["EmpID"].ToString(); 
        usercontrol.Name = (string)DR1["Name"]; 
        flowLayoutPanel1.Controls.Add(usercontrol); 
       } 
      } 
     } 

我如何將限制將在FlowLayoutPanel中顯示的記錄數？我知道有選擇頂部。但是，我將如何做到這一點，例如將顯示10條記錄，當點擊下一個按鈕時，將顯示接下來的10條記錄，當前一個按鈕點擊時，將顯示前10條記錄。

Answer 1

在SQL Server 2008中，你可以使用Row_Number()：

Select * from  
(Select row_number() over (order by EmpID) r, EmpID, Name from EmpTable) X 
where X.r between @start and @end 

供應的@start和@end的價值觀和你都設置。您可能會也可能不會顯示r的值。要從1-10顯示，請設置@start = 1和@end = 10依此類推。在這個查詢中，數據是在EmpID上訂購的。

修改後的代碼：

string a = "Select * from (Select row_number() over (order by EmpID) r, EmpID, Name from EmpTable) X where X.r between @start and @end"; 
     using (SqlCommand SqlCommand = new SqlCommand(" "+ a +" ", myDatabaseConnection)) 
     { 
      SqlCommand.Parameters.Add("@start").Value = 1; 
      SqlCommand.Parameters.Add("@end").Value = 10; 
      int i = 0; 
      SqlDataReader DR1 = SqlCommand.ExecuteReader(); 
      while (DR1.Read()) 
      { 
       i++; 
       BookUserControl usercontrol = new BookUserControl(); 
       usercontrol.Tag = i; 
       usercontrol.EmpID = DR1["EmpID"].ToString(); 
       usercontrol.Name = (string)DR1["Name"]; 
       flowLayoutPanel1.Controls.Add(usercontrol); 
      } 
     } 

見http://msdn.microsoft.com/en-us/library/ms186734(v=sql.90).aspx

Answer 2

是有SELECT TOP在SQL

使用這樣

Select TOP(10) EmpID, Name from EmpTable 

我更新你的鱈魚

flowLayoutPanel1.Controls.Clear(); 
     using (SqlConnection myDatabaseConnection = new SqlConnection(myConnectionString.ConnectionString)) 
     { 
      myDatabaseConnection.Open(); 
      string a = "SELECT TOP(10) EmpID, Name FROM EmpTable"; 
      using (SqlCommand SqlCommand = new SqlCommand(" "+ a +" ", myDatabaseConnection)) 
      { 
       int i = 0; 
       SqlDataReader DR1 = SqlCommand.ExecuteReader(); 
       while (DR1.Read()) 
       { 
        i++; 
        BookUserControl usercontrol = new BookUserControl(); 
        usercontrol.Tag = i; 
        usercontrol.EmpID = DR1["EmpID"].ToString(); 
        usercontrol.Name = (string)DR1["Name"]; 
        flowLayoutPanel1.Controls.Add(usercontrol); 
       } 
      } 
     } 

現在使用這個鱈魚和這正是你想要

工作

祝你好運

Answer 3

您最優雅是使用ROW_NUMBER函數

WITH NumberedMyTable AS 
(
    SELECT 
     Id, 
     Value, 
     ROW_NUMBER() OVER (ORDER BY Id) AS RowNumber 
    FROM 
     MyTable 
) 
SELECT 
    Id, 
    Value 
FROM 
    NumberedMyTable 
WHERE 
    RowNumber BETWEEN @From AND @To 

好運