C# 实现分页查询方法实例

namespace ConsoleApplication
{
/// <summary>
/// 定义查询类
/// </summary>
public class Query
{

public DateTime BeginTime = new DateTime(1900, 1, 1, 0, 0, 0);

public string Mackey = string.Empty;

public string DeviceNumber = string.Empty;

public string MarketName = string.Empty;

public int ProviderId = 0;

public int ModerId = 0;

public int PageNumber = 1;

public int PageSize = 0;

public bool ReturnCount = false;

/// <summary>
/// 默认构造函数
/// </summary>
public Query()
{
}

}

#region GetDeviceDetail
public static ProductInfoList GetDetail(Query query)
{
// 定义返回值数组list
ProductInfoList products = new ProductInfoList();
// 定义要查询的列名，方便查询count(*)时做替换
string fields = @"row_number() over (order by a.mackey) row, a.*, b.model_name, b.business_type, c.*, s.store_name";

// 定义分页查询的sql，条件默认为1=1，列名用占位符代替
string sql = @"select {0} from device a join device_model b on a.model_id=b.model_id
where 1=1 ";
// 定义一个条件sql stringbuilder
StringBuilder sb = new StringBuilder();

if (!string.IsNullOrEmpty(query.Mackey))
{
sb.Append(string.Format(" and a.mackey like '{0}%' ", query.Mackey.Trim()));
}

if (query.BeginTime != null && query.BeginTime != new DateTime(1900, 1, 1, 0, 0, 0))
{
DateTime beginDate = new DateTime(query.BeginTime.Year, query.BeginTime.Month, query.BeginTime.Day);
sb.AppendFormat(
" and a.register_date >='{0}'",
beginDate.ToString("yyyy-MM-dd"));
}

try
{
if (query.ReturnCount)
{
// 查询总总条数，满足条件的所有记录
object o = SqlHelper.ExecuteScalar(Conn.IOF, CommandType.Text, string.Format(sql + sb.ToString(), "count(*)"));
if (o != null)
{
products.MatchCount = Convert.ToInt32(o);
}
}
// 定义分页sql
string sqlOrder = string.Format(@"select * from ( {0} )  as products where row between {1}*({2}-1)+1 and {1}*{2}", string.Format(sql + sb.ToString(), fields), query.PageSize, query.PageNumber);

DataSet ds = SqlHelper.ExecuteDataset(Conn.IOF, CommandType.Text, sqlOrder);

if (ds != null && ds.Tables[0].Rows.Count > 0)
{
// 循环DT
foreach (DataRow dr in ds.Tables[0].Rows)
{
ProductInfo product = new ProductInfo();
product.Cost = Convert.ToDecimal(dr["cost"].ToString());
// 。。。。。。
products.Products.Add(product);
}
}
products.BaseResult.Code = 0;
}
catch (Exception ex)
{
products.BaseResult.Code = 401;
products.BaseResult.Message = ex.Message + ex.StackTrace + ex.InnerException;
log.ErrorException("GeDetail", ex);
}
return products;
}
#endregion
}