0311copy数据操作& 空字段处理

namespace Stu.Model
{
    public class StuModel
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public bool? Sex { get; set; }
        public DateTime? AddTime { get; set; }
    }
}
/////////////////////////////////////////////////////

using System.Data.SqlClient;

namespace Stu.DAL
{
using Stu.Model;

    public class StuDao
    {
        private string ConnStr = @"Data Source=********\SQL2008; Initial Catalog=Stu;Integrated Security=True";

        public void Add(StuModel entity)
        {
            string cmdText = "Insert Into Stu(Id,Name,Sex,AddTime) Values(@Id,@Name,@Sex,@AddTime)";

            using (SqlConnection conn = new SqlConnection(ConnStr))
            {
                SqlCommand cmd = new SqlCommand(cmdText, conn);
                DaoHelper.AddParameter(cmd, "@Id", entity.Id);
                DaoHelper.AddParameter(cmd, "@Name", entity.Name);
                DaoHelper.AddParameter(cmd, "@Sex", entity.Sex);
                DaoHelper.AddParameter(cmd, "@AddTime", entity.AddTime);
                conn.Open();
                cmd.ExecuteNonQuery();

}

        }
        public int MaxId()
        {
            string cmdText = "Select Max(Id) from Stu";
            using (SqlConnection conn = new SqlConnection(ConnStr))
            {
                SqlCommand cmd = new SqlCommand(cmdText, conn);
                conn.Open();
                var obj = cmd.ExecuteScalar();
                if (obj == null || obj is DBNull) return 1;

return (int)obj + 1;
}

        }
        public void Update(StuModel entity)
        {
            string cmdText = @"
                               Update Stu Set Name=@Name,Sex=@Sex,AddTime=@AddTime
                               Where Id=@Id
                              ";
            using (SqlConnection conn = new SqlConnection(ConnStr))
            {
                SqlCommand cmd = new SqlCommand(cmdText, conn);
                conn.Open();
                DaoHelper.AddParameter(cmd, "@Id", entity.Id);
                DaoHelper.AddParameter(cmd, "@Name", entity.Name);
                DaoHelper.AddParameter(cmd, "@Sex", entity.Sex);
                DaoHelper.AddParameter(cmd, "@AddTime", entity.AddTime);
                cmd.ExecuteNonQuery();

}

        }
        public void Del(int id)
        {
            //

            string cmdText = "Delete From stu Where Id=@Id ";
            using (SqlConnection conn = new SqlConnection(ConnStr))
            {
                SqlCommand cmd = new SqlCommand(cmdText, conn);
                cmd.Parameters.Add(new SqlParameter("@Id", id));
                conn.Open();
                cmd.ExecuteNonQuery();

            }
        }
        public StuModel Get(int id)
        {
            string cmdText = "Select * From stu Where Id=@Id ";

            StuModel model = null;
            using (SqlConnection conn = new SqlConnection(ConnStr))
            {

                SqlCommand cmd = new SqlCommand(cmdText, conn);
                DaoHelper.AddParameter(cmd, "@Id", id);
                conn.Open();
                using (IDataReader reader = cmd.ExecuteReader())
                {
                    if (reader.Read())
                    {
                        model = new StuModel();
                        model.Id = (int)reader["Id"];

                        model.Name = DaoHelper.GetValueFromReader<string>(reader, "Name");
                        model.Sex = DaoHelper.GetValueFromReader<bool?>(reader, "Sex");
                        model.AddTime = DaoHelper.GetValueFromReader<DateTime?>(reader, "AddTime");

}

return model;
}

public List<StuModel> GetAll()
{

            var list=new List<StuModel>();
            string cmdText = "Select * From Stu Order By Id";
            using (SqlConnection conn = new SqlConnection(ConnStr))
            {

                SqlCommand cmd = new SqlCommand(cmdText, conn);
                conn.Open();
                using (IDataReader reader = cmd.ExecuteReader())
                {
                    while(reader.Read())
                    {
                        var model = new StuModel();

model.Id = (int)reader["Id"];

list.Add(model);
}

}

}
return list;

}

}
}

/////////////////////////////////////////////////////

using System;
using System.Collections;
using System.Configuration;
using System.Data;
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.Data.SqlClient;

namespace Stu
{
using Stu.Model;
using Stu.DAL;

    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

}

        protected void Button1_Click(object sender, EventArgs e)
        {

                var dao = new StuDao();

                var entity = new StuModel();
                entity.Name = null;
                entity.Sex = null;
                entity.AddTime = null;
                entity.Id = dao.MaxId();

dao.Add(entity);
//dao.Update(entity);

                var list = dao.GetAll();
                foreach (var item in list)
                {

                    Response.Write(string.Format("Id:{0},Name:{1} <a href='StuDetai.aspx?id={0}' target='_blank'>查看</a><br/>",item.Id,item.Name ));
                }
                //model.Name = "张三";
                //dao.Update(model);

}

        protected void Button2_Click(object sender, EventArgs e)
        {
            SqlConnection conn = new SqlConnection(@"Data Source=**********\SQL2008; Initial Catalog=Stu;Integrated Security=True");
            SqlCommand cmd = new SqlCommand("UPADATA Stu SET Id=2 ",conn);

            conn.Open();
            cmd.ExecuteNonQuery();
            conn.Close();

}
}
}

////////////////////////////////////////////////////读可空字段

using System;
using System.Data;
using System.Configuration;
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.Data.SqlClient;
using System.ComponentModel;
namespace Stu.DAL
{
    public class DaoHelper
    {
        public static TResulte GetValueFromReader<TResulte>(IDataReader reader, string field)
        {
            var obj = reader[field];
            if (obj == null || obj is DBNull)
            {
                return default(TResulte);
            }
            return (TResulte)obj;

        }
        public static void AddParameter(SqlCommand cmd, string parameterName, object value)
        {
            SqlParameter parameter = new SqlParameter(parameterName, value);
            if (value == null)
            {
                parameter.IsNullable = true;
                parameter.Value = DBNull.Value;
            }
            cmd.Parameters.Add(parameter);
        }
    }
}

/////////////////////////////////////////////////////////////////

0311copy数据操作& 空字段处理

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