由于“int”类型的值永不等于“int?”类型的“null”,该表达式的结果始终为“true”
using System;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Collections.Generic;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Text;
using System.Data.OleDb;
using Maticsoft.DBUtility;//请先添加引用
namespace Maticsoft.DAL
{
/// <summary>
/// 数据访问类newsbig。
/// </summary>
public class newsbig
{
public static string connectionString = PubConstant.ConnectionString;
public newsbig()
{}
#region 成员方法
/// <summary>
/// 是否存在该记录
/// </summary>
public bool Exists(int id)
{
StringBuilder strSql=new StringBuilder();
strSql.Append("select count(1) from newsbig");
strSql.Append(" where id="+id+" ");
return DbHelperOleDb.Exists(strSql.ToString());
}
/// <summary>
/// 增加一条数据
/// </summary>
public void Add(Maticsoft.Model.newsbig model)
{
StringBuilder strSql=new StringBuilder();
StringBuilder strSql1=new StringBuilder();
StringBuilder strSql2=new StringBuilder();
if (model.id != null)
{
strSql1.Append("id,");
strSql2.Append(""+model.id+",");
}
if (model.newsclass != null)
{
strSql1.Append("newsclass,");
strSql2.Append("'"+model.newsclass+"',");
}
if (model.newsid != null)
{
strSql1.Append("newsid,");
strSql2.Append(""+model.newsid+",");
}
strSql.Append("insert into newsbig(");
strSql.Append(strSql1.ToString().Remove(strSql1.Length - 1));
strSql.Append(")");
strSql.Append(" values (");
strSql.Append(strSql2.ToString().Remove(strSql2.Length - 1));
strSql.Append(")");
DbHelperOleDb.ExecuteSql(strSql.ToString());
}
/// <summary>
/// 更新一条数据
/// </summary>
public void Update(Maticsoft.Model.newsbig model)
{
StringBuilder strSql=new StringBuilder();
strSql.Append("update newsbig set ");
if (model.id != null)
{
strSql.Append("id="+model.id+",");
}
if (model.newsclass != null)
{
strSql.Append("newsclass='"+model.newsclass+"',");
}
if (model.newsid != null)
{
strSql.Append("newsid="+model.newsid+",");
}
int n = strSql.ToString().LastIndexOf(",");
strSql.Remove(n, 1);
strSql.Append(" where id="+ model.id+" ");
DbHelperOleDb.ExecuteSql(strSql.ToString());
}
/// <summary>
/// 删除一条数据
/// </summary>
public void Delete(int id)
{
StringBuilder strSql=new StringBuilder();
strSql.Append("delete from newsbig ");
strSql.Append(" where id="+id+" " );
DbHelperOleDb.ExecuteSql(strSql.ToString());
}
/// <summary>
/// 得到一个对象实体
/// </summary>
public Maticsoft.Model.newsbig GetModel(int id)
{
StringBuilder strSql=new StringBuilder();
strSql.Append("select ");
strSql.Append(" id,newsclass,newsid ");
strSql.Append(" from newsbig ");
strSql.Append(" where id="+id+" " );
Maticsoft.Model.newsbig model=new Maticsoft.Model.newsbig();
DataSet ds=DbHelperOleDb.Query(strSql.ToString());
if(ds.Tables[0].Rows.Count>0)
{
if(ds.Tables[0].Rows[0]["id"].ToString()!="")
{
model.id=int.Parse(ds.Tables[0].Rows[0]["id"].ToString());
}
model.newsclass=ds.Tables[0].Rows[0]["newsclass"].ToString();
if(ds.Tables[0].Rows[0]["newsid"].ToString()!="")
{
model.newsid=int.Parse(ds.Tables[0].Rows[0]["newsid"].ToString());
}
return model;
}
else
{
return null;
}
}
/// <summary>
/// 获得数据列表
/// </summary>
public DataSet GetList(string strWhere)
{
StringBuilder strSql=new StringBuilder();
strSql.Append("select id,newsclass,newsid ");
strSql.Append(" FROM newsbig ");
if(strWhere.Trim()!="")
{
strSql.Append(" where "+strWhere);
}
return DbHelperOleDb.Query(strSql.ToString());
}
public List<Model.newsbig> get_List()
{
List<Model.newsbig> List = new List<Model.newsbig>();
DataTable dt = getDataSet("select * from newsbig where newsid=0 ").Tables[0];
foreach (DataRow dr in dt.Rows)
{
Model.newsbig model = new Model.newsbig();
model.id = Convert.ToInt32(dr["id"]);
model.newsclass = dr["newsclass"].ToString();
model.newsid = Convert.ToInt32(dr["newsid"]);
List.Add(model);
}
return List;
}
public List<Model.newsbig> get_List(string ParentID)
{
List<Model.newsbig> List = new List<Model.newsbig>();
DataTable dt = getDataSet("select * from newsbig where newsid=" + ParentID + " ").Tables[0];
foreach (DataRow dr in dt.Rows)
{
Model.newsbig model = new Model.newsbig();
model.id = Convert.ToInt32(dr["id"]);
model.newsclass = dr["newsclass"].ToString();
model.newsid = Convert.ToInt32(dr["newsid"]);
List.Add(model);
}
return List;
}
protected DataSet getDataSet(string sql)
{
OleDbConnection conn = new OleDbConnection(connectionString);
conn.Open();
OleDbCommand cmd = new OleDbCommand(sql, conn);
OleDbDataAdapter da = new OleDbDataAdapter();
da.SelectCommand = cmd;
DataSet ds = new DataSet();
da.Fill(ds);
conn.Close();
return ds;
}
public DataTable GetAll(int id)
{
StringBuilder strSql = new StringBuilder();
strSql = new StringBuilder();
strSql.Append("select * from newsbig where newsid=" + id + "");
return DbHelperOleDb.Fill(strSql.ToString());
}
/*
*/
#endregion 成员方法
}
}
应该如何修改?