Sql选择语句与寻呼c＃

Question

在c＃控制器上编写选择语句以进行分页的正确方法是什么？这是我想出了最好的，但我知道这是行不通的，因为它显示我对电网的第一页上的所有数据......请帮助

public JsonResult getData(int start, int limit) 
{ 
    List<MyItem> items = new List<MyItem>(); 
    using (SqlConnection con = new  SqlConnection(ConfigurationManager.ConnectionStrings["ApplicationServices1"].ConnectionString)) 
{ 
SqlCommand cmd = con.CreateCommand(); 
cmd.CommandText = "SELECT State, Capital FROM MYDBTABLE"; 
con.Open(); 
SqlDataReader reader = cmd.ExecuteReader(); 
while (reader.Read()) 
{ 
    MyItem item = new MyItem(); 
    item.State = reader[0].ToString(); 
    item.Capital = reader[1].ToString(); 
    items.Add(item); 
} 
con.Close(); 

if ((start + limit) > Myitem.Count) 
{ 
    limit = Myitem.Count - start; 
} 
return Json(new { myTable = items }, JsonRequestBehavior.AllowGet); 
} 
} 

Answer 1

下面是我喜欢存储的特效模板用于分页。

CREATE PROCEDURE [dbo].[StoredProcName] 
    @page_size INT 
    , @page_num INT 
AS 
BEGIN 

    SET NOCOUNT ON; 

    ; WITH RESULTS AS 
    (
     SELECT * 
      , ROW_NUMBER() OVER (ORDER BY <order_col> DESC) AS rn 
      , ROW_NUMBER() OVER (ORDER BY <order_col> ASC) AS rn_reversed 
     FROM <table> 
    ) 
    SELECT * 
     , CAST(rn + rn_reversed - 1 AS INT) AS total_rows 
     , CAST(CASE (rn + rn_reversed - 1) % @page_size 
      WHEN 0 THEN (rn + rn_reversed - 1)/@page_size 
      ELSE ((rn + rn_reversed - 1)/@page_size) + 1 
      END AS INT) AS total_pages 
    FROM RESULTS a 
    WHERE a.rn BETWEEN 1 + ((@page_num - 1) * @page_size) AND @page_num * @page_size 
    ORDER BY rn ASC 

END 

你只需要在page_size和page_num传递到存储过程，你是好去。

Answer 2

我使用的基本模板是：

SELECT ROW_NUMBER(), <Rest of your columns> 
FROM <Your Tables/Joins> 
WHERE ROW_NUMBER() >= (@PageNum * @RowsPerPage) 
AND ROW_NUMBER() < (@PageNum+1 * @RowsPerPage) 

Answer 3

你可以使用LINQ和使用Skip()和Take()这样的：

public JsonResult getData(int page, int limit) 
{ 
    DataTable dt = new DataTable(); 
    using (SqlConnection cnn = new SqlConnection(ConfigurationManager.ConnectionStrings["ApplicationServices1"].ConnectionString)) 
    { 
     using (SqlCommand cmd = cnn.CreateCommand()) 
     { 
      cmd.CommandType = CommandType.Text; 
      cmd.CommandText = "SELECT State, Capital FROM MYDBTABLE"; 
      using (SqlDataAdapter da = new SqlDataAdapter(cmd)) 
      { 
       da.Fill(dt); 
      } 
     } 
    } 
    int start = (page * limit) - limit; 
    List<MyItem> items = (from DataRow row in dt.Rows 
          select new MyItem 
          { 
           State = row["State"].ToString(), 
           Capital = row["Capital"].ToString() 
          }).Skip(start - 1).Take(limit).ToList(); 
    return Json(new { myTable = items }, JsonRequestBehavior.AllowGet); 
}