SqlHelper.cs 类

using System;
using System.Collections.Generic;
using System.Text;
//引入必须的命名空间
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace DAL
{
    public class SqlHelper
    {
        #region 静态私有变量
        /// <summary>
        /// SqlConnection 对象实例
        /// </summary>
        private static SqlConnection conn;

        #endregion

        #region 共有方法
        /// <summary>
        /// 返回一个未打开的数据库连接类
        /// </summary>
        /// <returns></returns>
        private static void InitConn()
        {
            conn = new SqlConnection(System.Configuration.ConfigurationManager.AppSettings["dbstr"].ToString());
        }
        /// <summary>
        /// 实例化一个执行T-Sql语句的SqlCommand对象实例
        /// </summary>
        /// <param name="que">要执行的SQL语句</param>
        /// <returns></returns>
        private static SqlCommand BuildCommand(string que)
        {
            InitConn();
            try
            {
                if (conn.State == ConnectionState.Closed)
                    conn.Open();

                SqlCommand cmd = new SqlCommand(que, conn);
                return cmd;
            }
            catch(SqlException EX)
            {
                throw EX;
            }
           
        }

        /// <summary>
        /// 构建 SqlCommand 对象(用来返回一个结果集，而不是一个整数值)
        /// </summary>
        /// <param name="connection">数据库连接</param>
        /// <param name="storedProcName">存储过程名</param>
        /// <param name="parameters">存储过程参数</param>
        /// <returns>SqlCommand</returns>
        private static SqlCommand BuildCommand(string storedProcName, IDataParameter[] parameters)
        {
            InitConn();
            conn.Open();
            SqlCommand cmd = new SqlCommand(storedProcName, conn);
            cmd.CommandType = CommandType.StoredProcedure;
            foreach (SqlParameter parameter in parameters)
            {
                if (parameter != null)
                {
                    // 检查未分配值的输入参数,将其分配以DBNull.Value.
                    if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) && (parameter.Value == null))
                    {
                        parameter.Value = DBNull.Value;
                    }
                    cmd.Parameters.Add(parameter);
                }
            }

            return cmd;
        }

        /// <summary>
        /// 创建 SqlCommand 对象实例(用来返回一个整数值) 
        /// </summary>
        /// <param name="storedProcName">存储过程名</param>
        /// <param name="parameters">存储过程参数</param>
        /// <returns>SqlCommand 对象实例</returns>
        private static SqlCommand BuildIntCommand(string storedProcName, IDataParameter[] parameters)
        {
            SqlCommand cmd = BuildCommand(storedProcName, parameters);
            cmd.Parameters.Add(new SqlParameter("ReturnValue",
                SqlDbType.Int, 4, ParameterDirection.ReturnValue,
                false, 0, 0, string.Empty, DataRowVersion.Default, null));
            return cmd;
        }

        /// <summary>
        /// 关闭连接和CMD命令并清理资源
        /// </summary>
        private static void CloseConn()
        {
            if (conn != null)
            {
                if (conn.State == ConnectionState.Open)
                {
                    conn.Close();
                    conn.Dispose();
                }
            }
        }
        #endregion

        #region  执行T-Sql语句访问数据库
        /// <summary>
        /// 执行指定的SQL语句，返回受影响的行数
        /// </summary>
        /// <param name="query">查询的SQL语句</param>
        /// <returns></returns>
        public static int ExecuteNonQuery(string query)
        {
            SqlCommand cmd = BuildCommand(query);
            int i = cmd.ExecuteNonQuery();
            CloseConn();
            return i;
        }
        /// <summary>
        /// 执行一个T-SQL查询，返回首行首列
        /// </summary>
        /// <param name="query">查询的SQL语句</param>
        /// <returns></returns>
        public static object ExecuteScalar(string query)
        {
            SqlCommand cmd = BuildCommand(query);
            object obj = cmd.ExecuteScalar();
            CloseConn();
            return obj;
        }
        /// <summary>
        /// 执行一个T-SQL查询，返回DataReader对象
        /// </summary>
        /// <param name="query">查询的SQL语句</param>
        /// <returns></returns>
        public static SqlDataReader ExecuteReader(string query)
        {
            SqlCommand cmd = BuildCommand(query);
            SqlDataReader sdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
            return sdr;
        }
        /// <summary>
        /// 执行一个T-SQL查询，返回DataSet对象
        /// </summary>
        /// <param name="query">查询的SQL语句</param>
        /// <param name="TableName">DataSet结果中的表名</param>
        /// <returns></returns>
        public static DataSet GetList(string query,string TableName)
        {
            InitConn();
            SqlDataAdapter sda = new SqlDataAdapter(query, conn);
            DataSet ds = new DataSet();
            sda.Fill(ds, TableName);
            CloseConn();
            return ds;
        }
        #endregion

        #region 执行存储过程访问数据库
        /// <summary>
        /// 执行指定的存储过程并返回受影响的行
        /// </summary>
        /// <param name="query">要调用的存储过程名</param>
        /// <param name="para">参数集合</param>
        /// <returns></returns>
        public static int ExecuteNonQuery(string query, IDataParameter[] para)
        {
            SqlCommand cmd = BuildIntCommand(query, para);
            int i = cmd.ExecuteNonQuery();
            CloseConn();
            return i;
        }
        /// <summary>
        /// 执行有返回参数的存储过程
        /// </summary>
        /// <param name="storedProcName">存储过程名</param>
        /// <param name="parameters">存储过程参数</param>
        /// <param name="rowsAffected">影响的行数</param>
        /// <returns></returns>
        public static int ExecuteNonQuery(string query, IDataParameter[] para, out int rowsAffected)
        {
            SqlCommand cmd = BuildIntCommand(query, para);
            rowsAffected = cmd.ExecuteNonQuery();
            int result = (int)cmd.Parameters["ReturnValue"].Value;
            CloseConn();
            return result;
        }
        /// <summary>
        /// 调用存储过程执行一个查询，返回首行首列
        /// </summary>
        /// <param name="query">要调用的存储过程名</param>
        /// <param name="para">参数集合</param>
        /// <returns></returns>
        public static object ExecuteScalar(string query, IDataParameter[] para)
        {
            SqlCommand cmd = BuildCommand(query, para);
            object obj = cmd.ExecuteScalar();
            CloseConn();
            return obj;
        }
        /// <summary>
        /// 调用存储过程执行查询，返回DataReader对象
        /// </summary>
        /// <param name="query">要调用的存储过程名</param>
        /// <param name="para">参数集合</param>
        /// <returns></returns>
        public static SqlDataReader ExecuteReader(string query, IDataParameter[] para)
        {
            SqlCommand cmd = BuildCommand(query, para);
            SqlDataReader sdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
           
            return sdr;
        }
        /// <summary>
        /// 执行一个T-SQL查询，返回DataSet对象
        /// </summary>
        /// <param name="query">存储过程名</param>
        /// <param name="para">存储过程参数</param>
        /// <param name="TableName">DataSet结果中的表名</param>
        /// <returns></returns>
        public static DataSet GetList(string query,IDataParameter[] para, string TableName)
        {
            SqlDataAdapter sda = new SqlDataAdapter();
            sda.SelectCommand = BuildCommand(query, para);
            DataSet ds = new DataSet();
            sda.Fill(ds, TableName);
            CloseConn();
            return ds;
        }
        #endregion
    }
}