请教SqlHelper类问题

Question

想做一个SqlHelper类，里面包含显示、添加、修改和删除数据的方法，方便调用。不知怎么写？
类似下面这样：
public class SqlHelper
{
    //获取连接字符串
    public static readonly string ConnectionString = ConfigurationManager.ConnectionStrings["LocalSqlServer"].ConnectionString;
//用哈希表存储缓存的参数信息
    private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());
    public SqlHelper()
{
//
// TODO: 在此处添加构造函数逻辑
//
}
  public static DataSet FillDataSet(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
    {
        SqlCommand cmd = new SqlCommand();
        SqlConnection conn = new SqlConnection(connectionString);
        try
        {
            PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
            SqlDataAdapter adp=new SqlDataAdapter ();
            adp.SelectCommand = cmd;
            DataSet ds=new DataSet ();
            adp.Fill(ds);//, "Table1"
            conn.Close();
            if (ds.Tables[0].Rows.Count > 0)
                return ds;
            else return null;
        }
        catch 
        {
            conn.Close ();
            throw ;
        }
    }
还有我想用DataList控件显示数据，在SqlHelper类中能不能像下面这样写？
public bool ecadabind(GridView gv, string sqlstr4)
    {
        SqlConnection con = this.getcon();
        con.Open();
        SqlDataAdapter mydataadapter = new SqlDataAdapter(sqlstr4, con);
        DataSet mydataset = new DataSet();
        mydataadapter.Fill(mydataset);
        gv.DataSource = mydataset;
        try
        {
            gv.DataBind();
            return true;
        }
}
谢谢！！

Answer 1

using System;
using System.Collections.Generic;
using System.Text;using System.Data;
using System.Data.SqlClient;
using System.Reflection;
using System.Configuration;namespace DAL
{
    public class SqlHelper
    {
        #region 变量
        private static SqlConnection con = null;
        private static string assemblyName = "Model";
        public static string constr = ConfigurationManager.ConnectionStrings["connData"].ConnectionString;
        #endregion        #region 属性
        public static SqlConnection Con
        {
            get
            {
                if (SqlHelper.con == null)
                {
                    SqlHelper.con = new SqlConnection();
                }
                if (SqlHelper.con.ConnectionString == "")
                {
                    SqlHelper.con.ConnectionString = SqlHelper.constr;
                }
                return SqlHelper.con;
            }
            set
            {
                SqlHelper.con = value;
            }
        }
        #endregion        #region 方法
        #region 查询单个
        public static int ExecuteScalar(string sql, CommandType commandTypeName, params SqlParameter[] p)
        {
            int count = 0;
            using (SqlHelper.Con)
            {
                using (SqlCommand cmd = new SqlCommand(sql, SqlHelper.Con))
                {
                    try
                    {
                        cmd.CommandType = commandTypeName;
                        if (p != null)
                        {
                            cmd.Parameters.AddRange(p);
                        }
                        SqlHelper.Con.Open();
                        count = Convert.ToInt32(cmd.ExecuteScalar());
                    }
                    catch (Exception ex)
                    {
                        throw ex;
                    }
                }
            }
            return count;
        }
        #endregion
        #region 增删改
        public static int ExecuteNonQuery(string sql, CommandType commandTypeName, params SqlParameter[] p)
        {
            int result = 0;
            using (SqlHelper.Con)
            {
                using (SqlCommand cmd = new SqlCommand(sql, SqlHelper.Con))
                {
                    cmd.CommandType = commandTypeName;
                    if (p != null)
                    {
                        cmd.Parameters.AddRange(p);
                        SqlHelper.Con.Open();
                        result = cmd.ExecuteNonQuery();
                    }
                }
            }
            return result;        }
        #endregion
        #region 读取结果集
        private static T ResultSet<T>(IDataReader reader)
        {
            T obj = default(T);
            try
            {
                Type type = typeof(T);
                obj = (T)Assembly.Load(SqlHelper.assemblyName).CreateInstance(type.FullName);
                PropertyInfo[] ps = type.GetProperties();                foreach (PropertyInfo p in ps)
                {
                    for (int i = 0; i < reader.FieldCount; i++)
                    {
                        string filedName = reader.GetName(i);//
                        if (filedName.ToLower() == p.Name.ToLower())
                        {
                            Object v = reader[filedName];
                            if (v != null && v != DBNull.Value)
                            {
                                p.SetValue(obj, v, null);
                                break;
                            }
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
            return obj;        }
        #endregion
        #region 查询所有
        public static List<T> ExecuteList<T>(string sql, CommandType commandType, params SqlParameter[] param)
        {
            List<T> list = new List<T>();
            using (SqlHelper.Con)
            {
                using (SqlCommand cmd = new SqlCommand(sql, SqlHelper.Con))
                {
                    try
                    {
                        cmd.CommandType = commandType;
                        if (param != null)
                        {
                            cmd.Parameters.AddRange(param);
                        }
                        SqlHelper.Con.Open();
                        SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                        while (reader.Read())
                        {
                            T obj = SqlHelper.ResultSet<T>(reader);
                            list.Add(obj);
                        }
                    }
                    catch (Exception ex)
                    {
                        throw ex;
                    }
                }
            }
            return list;
        }
        #endregion
        #region 查询单个数据
        public static T ExecuteEntity<T>(string commandText, CommandType commandType, params SqlParameter[] param)
        {
            T obj = default(T);
            using (SqlHelper.Con)
            {
                using (SqlCommand cmd = new SqlCommand(commandText, SqlHelper.Con))
                {
                    cmd.CommandType = commandType;
                    if (param != null)
                    {
                        cmd.Parameters.AddRange(param);
                    }
                    SqlHelper.Con.Open();
                    SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                    while (reader.Read())
                    {
                        obj = SqlHelper.ResultSet<T>(reader);
                    }
                }            }
            return obj;
        }
        #endregion
        #endregion
    }
}

Answer 2

可以这样写。但是这样写没什么意义的。
页面上的控件直接绑定这个方法
gv.DataSource = FillDataSet（）;
gv.DataBind();

Answer 3

谢谢，我想做一个登录页面，后台这样写有什么问题？
string UserName = name.Text.Trim();
        string PassWord = pwd.Text.Trim();
        string sql = "select * from Admin  where admin='" + UserName + "' and password='" + PassWord + "'";
        DataSet ds = SqlHelper.FillDataSet(SqlHelper.ConnectionString, CommandType.Text, sql, null);        if (ds.Tables[0].Rows.Count > 0)
        {
            Session["adminname"] = this.name.Text;
            Response.Write("<script>location.href=('admin_main.htm');</script>");
        }
        else
        {
            MessageBox.ShowAndRedirect(this, "用户名或密码错误！", "default.aspx");
        }

Answer 4

  /******************************    ******************************/
    public class SqlHelper
    {
        private static SqlConnection cn = null;
        private static SqlCommand cmd = null;        public SqlHelper()
        {        }        /// <summary>
        /// 判断连接状态
        /// </summary>
        /// <returns>返回连接状态</returns>
        private static SqlConnection GetConn()
        {
            string ConnStr = M_Common.Helper.ConfigHelper.GetconnMsSql.ToString();
            cn = new SqlConnection(ConnStr);
            if (cn.State != ConnectionState.Open)
            {
                cn.Open();
            }
            return cn;
        }
        /// <summary>
        /// 获取某表的某个字段的最大值
        /// </summary>
        /// <param name="FieldName">字段名</param>
        /// <param name="TableName">表明</param>
        /// <returns>返回最大值</returns>
        public static int GetMaxID(string FieldName, string TableName)
        {
            string strsql = "select max(" + FieldName + ")+1 from " + TableName;
            object obj = SqlHelper.GetSingle(strsql);
            if (obj == null)
            {
                return 1;
            }
            else
            {
                return int.Parse(obj.ToString());
            }
        }
        /// <summary>
        /// 执行一条计算查询结果语句，返回查询结果（object）。
        /// </summary>
        /// <param name="SQLString">计算查询结果语句</param>
        /// <returns>查询结果（object）</returns>
        public static object GetSingle(string SQLString)
        {
            using (SqlCommand cmd = new SqlCommand(SQLString, GetConn()))
            {
                try
                {
                    object obj = cmd.ExecuteScalar();
                    if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
                    {
                        return null;
                    }
                    else
                    {
                        return obj;
                    }
                }
                catch (System.Data.SqlClient.SqlException e)
                {
                    throw e;
                }
            }        }        /// <summary>
        /// 带参数返回一行一列ExecuteScalar
        /// </summary>
        /// <param name="cmdtext">存储过程或者SQL语句</param>
        /// <param name="para">参数数组</param>
        /// <param name="ct">命令类型</param>
        /// <returns>返回一行一列value</returns>
        public static int ExecuteScalar(string cmdtext, SqlParameter[] para, CommandType ct)
        {
            int value;
            try
            {
                cmd = new SqlCommand(cmdtext, GetConn());
                cmd.CommandType = ct;
                cmd.Parameters.AddRange(para);
                value = Convert.ToInt32(cmd.ExecuteScalar());
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (cn.State == ConnectionState.Open)
                {
                    cn.Close();
                }
            }
            return value;
        }
        /// <summary>
        /// 执行无参的操作
        /// </summary>
        /// <param name="cmdtext">SQL语句或存储过程</param>
        /// <param name="ct">CMD的类型</param>
        /// <returns>处理后的值</returns>
        public static int ExecuteNonQuery(string cmdtext, CommandType ct)
        {
            int value;
            try
            {
                cmd = new SqlCommand(cmdtext, GetConn());
                cmd.CommandType = ct;
                value = cmd.ExecuteNonQuery() > 0 ? 1 : 0;
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (cn.State == ConnectionState.Open)
                {
                    cn.Close();
                }
            }
            return value;
        }        /// <summary>
        /// 执行带参的增.删.改操作
        /// </summary>
        /// <param name="cmdtext">SQL语句或存储过程</param>
        /// <param name="para">参数数组</param>
        /// <param name="ct">CMD类型</param>
        /// <returns>处理后的值</returns>
        public static int ExecuteNonQuery(string cmdtext, SqlParameter[] para, CommandType ct)
        {
            int value;
            using (cmd = new SqlCommand(cmdtext, GetConn()))
            {
                cmd.CommandType = ct;
                cmd.Parameters.AddRange(para);
                value = cmd.ExecuteNonQuery() > 0 ? 1 : 0;
            }
            return value;
        }        /// <summary>
        /// 执行无参的查询 返回DataTable
        /// </summary>
        /// <param name="cmdtext">存储过程名称或SQL语句</param>
        /// <param name="ct">命令类型</param>
        /// <returns>返回DataTable</returns>
        public static DataTable ReturnDataTable(string cmdtext, CommandType ct)
        {
            DataTable dt = new DataTable();
            cmd = new SqlCommand(cmdtext, GetConn());
            //类型
            cmd.CommandType = ct;
            SqlDataReader dr = null;
            //连接池 读完自动释放Connection
            using (dr = cmd.ExecuteReader(CommandBehavior.CloseConnection))
            {
                //用委托填充DataTable
                dt.Load(dr);
            }
            return dt;
        }        /// <summary>
        /// 执行有参的查询 返回DataTable
        /// </summary>
        /// <param name="cmdtext">存储过程名称或SQL语句</param>
        /// <param name="ct">命令类型</param>
        /// <param name="para">参数数组</param>
        /// <returns>返回DataTable</returns>
        public static DataTable ReturnDataTable(string cmdtext, CommandType ct, SqlParameter[] para)
        {
            DataTable dt = new DataTable();
            cmd = new SqlCommand(cmdtext, GetConn());
            //类型
            cmd.CommandType = ct;
            //参数数组
            cmd.Parameters.AddRange(para);
            SqlDataReader dr = null;
            //连接池 读完自动释放Connection
            using (dr = cmd.ExecuteReader(CommandBehavior.CloseConnection))
            {
                //用委托填充DataTable
                dt.Load(dr);
            }
            return dt;
        }        /// <summary>
        /// 执行无参的查询 返回DataSet
        /// </summary>
        /// <param name="cmdtext">存储过程名称或SQL语句</param>
        /// <param name="ct">命令类型</param>
        /// <returns>返回DataSet</returns>
        public static DataSet ReturnDataSet(string cmdtext, CommandType ct)
        {
            cmd = new SqlCommand(cmdtext, GetConn());
            //类型
            cmd.CommandType = ct;
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            try
            {
                da.Fill(ds);
            }
            catch (Exception err)
            {                throw err;
            }
            finally
            {
                if (cn.State != ConnectionState.Closed)
                {
                    cn.Close();
                }
            }
            return ds;
        }
        /// <summary>
        /// 执行有参的查询 返回DataSet
        /// </summary>
        /// <param name="cmdtext">存储过程名称或SQL语句</param>
        /// <param name="ct">命令类型</param>
        /// <param name="para">参数数组</param>
        /// <returns>返回DataSet</returns>
        public static DataSet ReturnDataSet(string cmdtext, CommandType ct, SqlParameter[] para)
        {
            cmd = new SqlCommand(cmdtext, GetConn());
            //类型
            cmd.CommandType = ct;
            //参数数组
            cmd.Parameters.AddRange(para);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            try
            {
                da.Fill(ds);
            }
            catch (Exception err)
            {                throw err;
            }
            finally
            {
                if (cn.State != ConnectionState.Closed)
                {
                    cn.Close();
                }
            }
            return ds;
        }    }没啥问题 最好用ExecuteScalar来判断。

Answer 5

但是出现错误提示哦
CS0103: 当前上下文中不存在名称“MessageBox”
我加了using System.Windows.Forms;后又提示
“System”中不存在类型或命名空间名称“Windows”(是缺少程序集引用吗?)
原来用ACCESS数据库是没这个提示的哦？
另ExecuteScalar来判断怎么去判断？谢谢！！

Answer 6

上面问题解决了。还有最后一个问题：我添加数据时调用代码如下：
 string sql = "insert into info(title,classid,nclassid,DefaultPic,pic,author,content,writefrom,address,waddress,flag) values('" + title + "'," + classid + "," + nclassid + ",'" + DefaultPic + "'," + pic + ",'" + author + "','" + content + "','" + writefrom + "','" + address + "','" + waddress + "'," + vflag + ")";
        int cmd=SqlHelper.ExecuteNonQuery(SqlHelper.ConnectionString, CommandType.Text, sql, null);
这样调用行不行？怎么会出现这样的提示:
回发或回调参数无效。在配置中使用 <pages enableEventValidation="true"/>.......

Answer 7

http://blog.csdn.net/LCL_data/archive/2009/07/19/4361258.aspx