dbhelp

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

namespace  DBUtils
{

    /// <summary>
    /// 基于数据库SQL SERVER的常规数据库操作
    /// 本类修改自Mirosoft .NET Pet Shop 4.0 的数据库操作通用类
    /// 修改:icefire @ 20070213
    /// </summary>
    public abstract class SqlHelper
    {
        // 哈希表保存数据库参数
        private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());

        #region 常规数据库操作

        #region 执行非查询语句
        /// <summary>
        /// 通过数据库字符串链接执行非查询语句，如INSERT,UPDATE,DEL等操作
        /// </summary>
        /// <remarks>
        /// 例如：
        /// int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
        /// </remarks>
        /// <param name="connectionString">数据库链接字符串</param>
        /// <param name="cmdType">SQL命令类型，如存储过程，文本语句等</param>
        /// <param name="cmdText">SQL命令字符串</param>
        /// <param name="commandParameters">SQL参数数组</param>
        /// <returns>返回处理结果</returns>
        public static int ExecuteNonQuery(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {

            SqlCommand cmd = new SqlCommand();

            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
                int val = cmd.ExecuteNonQuery();
                cmd.Parameters.Clear();
                return val;
            }
        }

        /// <summary>
        /// 通过已经存在的数据库链接执行非查询语句，如INSERT,UPDATE,DEL等操作
        /// </summary>
        /// <remarks>
        /// 例如
        ///  int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
        /// </remarks>
        /// <param name="connection">数据库链接对象</param>
        /// <param name="cmdType">SQL命令类型，如存储过程，文本语句等</param>
        /// <param name="cmdText">SQL命令字符串</param>
        /// <param name="commandParameters">SQL参数数组</param>
        /// <returns>返回处理结果</returns>
        public static int ExecuteNonQuery(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {

            SqlCommand cmd = new SqlCommand();

            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
            int val = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return val;
        }

        /// <summary>
        /// 以 Transact-SQL 事务方式执行非查询语句
        /// </summary>
        /// <param name="trans">事务对象</param>
        /// <param name="cmdType">SQL命令类型，如存储过程，文本语句等</param>
        /// <param name="cmdText">SQL命令字符串</param>
        /// <param name="commandParameters">SQL参数数组</param>
        /// <returns>返回处理结果</returns>
        public static int ExecuteNonQuery(SqlTransaction trans, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, commandParameters);
            int val = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return val;
        }
        #endregion

        #region 查询数据库操作并返回结果
        /// <summary>
        /// 通过数据库链接字符串执行查询命令并返回查询结果
        /// </summary>
        /// <param name="connectionString">数据库链接字符串</param>
        /// <param name="cmdType">命令类型</param>
        /// <param name="cmdText">命令字符串</param>
        /// <param name="commandParameters">SQL参数数组</param>
        /// <returns>返回SqlDataReader对象</returns>
        public static SqlDataReader ExecuteReader(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);
                SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                cmd.Parameters.Clear();
                return rdr;
            }
            catch
            {
                conn.Close();
                throw;
            }
        }
        #endregion

        #region 执行语句返回第一行，第一列的值
        /// <summary>
        /// 执行查询并返回结果集的第一行的第一列,次执行效率较高
        /// </summary>
        /// <param name="connectionString">数据库链接字符串</param>
        /// <param name="cmdType">命令类型</param>
        /// <param name="cmdText">命令字符串</param>
        /// <param name="commandParameters">SQL参数数组</param>
        /// <returns>返回结果对象</returns>
        public static object ExecuteScalar(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();

            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
                object val = cmd.ExecuteScalar();
                cmd.Parameters.Clear();
                return val;
            }
        }

        /// <summary>
        /// 执行查询并返回结果集的第一行的第一列,次执行效率较高
        /// </summary>
        /// <param name="connection">数据库连接对象</param>
        /// <param name="cmdType">命令类型</param>
        /// <param name="cmdText">命令字符串</param>
        /// <param name="commandParameters">SQL参数数组</param>
        /// <returns>返回结果对象</returns>
        public static object ExecuteScalar(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {

            SqlCommand cmd = new SqlCommand();

            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
            object val = cmd.ExecuteScalar();
            cmd.Parameters.Clear();
            return val;
        }
        #endregion

        #endregion

        #region 将查询结果保存到DataSet中
        /// <summary>
        /// 根据数据库连接字符串执行查询并返回结果DataSet
        /// </summary>
        /// <param name="connectionString">数据库链接字符串</param>
        /// <param name="cmdType">命令类型</param>
        /// <param name="cmdText">命令字符串</param>
        /// <param name="commandParameters">SQL参数数组</param>
        /// <returns>返回结果</returns>
        public static DataSet ExecuteDataSet(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlDataAdapter da = new SqlDataAdapter();

            SqlCommand cmd = new SqlCommand();

            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                DataSet dsReturn = new DataSet();

                //准备Command命令
                PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);

                //执行命令
                da.SelectCommand = cmd;
                da.Fill(dsReturn);

                cmd.Parameters.Clear();
                return dsReturn;
            }
        }

        /// <summary>
        /// 根据数据库连接执行查询并返回结果DataSet
        /// </summary>
        /// <param name="connection">数据库连接对象</param>
        /// <param name="cmdType">命令类型</param>
        /// <param name="cmdText">命令字符串</param>
        /// <param name="commandParameters">SQL参数数组</param>
        /// <returns>返回结果</returns>
        public static DataSet ExecuteDataSet(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlDataAdapter da = new SqlDataAdapter();

            SqlCommand cmd = new SqlCommand();

            DataSet dsReturn = new DataSet();

            //准备Command命令
            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);

            //执行命令
            da.SelectCommand = cmd;
            da.Fill(dsReturn);

            cmd.Parameters.Clear();
            return dsReturn;
        }
        #endregion

        #region 将查询结果保存到DataTable中
        /// <summary>
        /// 根据数据库连接字符串执行查询并返回结果DataTable
        /// </summary>
        /// <param name="connectionString">数据库链接字符串</param>
        /// <param name="cmdType">命令类型</param>
        /// <param name="cmdText">命令字符串</param>
        /// <param name="commandParameters">SQL参数数组</param>
        /// <returns>返回结果</returns>
        public static DataTable ExecuteDataTable(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlDataAdapter da = new SqlDataAdapter();

            SqlCommand cmd = new SqlCommand();

            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                DataTable dtReturn = new DataTable();

                //准备Command命令
                PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);

                //执行命令
                da.SelectCommand = cmd;
                da.Fill(dtReturn);

                cmd.Parameters.Clear();
                return dtReturn;
            }
        }

        /// <summary>
        /// 根据数据库连接执行查询并返回结果DataTable
        /// </summary>
        /// <param name="connection">数据库连接对象</param>
        /// <param name="cmdType">命令类型</param>
        /// <param name="cmdText">命令字符串</param>
        /// <param name="commandParameters">SQL参数数组</param>
        /// <returns>返回结果</returns>
        public static DataTable ExecuteDataTable(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlDataAdapter da = new SqlDataAdapter();

            SqlCommand cmd = new SqlCommand();

            DataTable dtReturn = new DataTable();

            //准备Command命令
            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);

            //执行命令
            da.SelectCommand = cmd;
            da.Fill(dtReturn);

            cmd.Parameters.Clear();
            return dtReturn;
        }
        #endregion

        #region 数据库命令数组缓存操作
        /// <summary>
        /// 增加数据库超作参数到缓存
        /// </summary>
        /// <param name="cacheKey">缓存健</param>
        /// <param name="cmdParms">被缓存的SQL参数数组</param>
        public static void CacheParameters(string cacheKey, params SqlParameter[] commandParameters)
        {
            parmCache[cacheKey] = commandParameters;
        }

        /// <summary>
        /// 根据缓存健得到缓存的命令数组
        /// </summary>
        /// <param name="cacheKey">缓存健</param>
        /// <returns>被缓存的SQL参数数组</returns>
        public static SqlParameter[] GetCachedParameters(string cacheKey)
        {
            SqlParameter[] cachedParms = (SqlParameter[])parmCache[cacheKey];

            if (cachedParms == null)
                return null;

            SqlParameter[] clonedParms = new SqlParameter[cachedParms.Length];

            for (int i = 0, j = cachedParms.Length; i < j; i++)
                clonedParms[i] = (SqlParameter)((ICloneable)cachedParms[i]).Clone();

            return clonedParms;
        }
        #endregion

        #region 对SQL命令预处理
        /// <summary>
        /// 准备一个执行命令
        /// </summary>
        /// <param name="cmd">数据库命令字对象</param>
        /// <param name="conn">数据库链接对象</param>
        /// <param name="trans">数据库事务对象</param>
        /// <param name="cmdType">SQL命令类型，如存储过程，文本语句等</param>
        /// <param name="cmdText">SQL命令字符串</param>
        /// <param name="cmdParms">SQL参数数组</param>
        private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, CommandType cmdType, string cmdText, SqlParameter[] cmdParms)
        {

            if (conn.State != ConnectionState.Open)
                conn.Open();

            cmd.Connection = conn;
            cmd.CommandText = cmdText;

            if (trans != null)
                cmd.Transaction = trans;

            cmd.CommandType = cmdType;

            if (cmdParms != null)
            {
                foreach (SqlParameter parm in cmdParms)
                    cmd.Parameters.Add(parm);
            }
        }
        #endregion
    }
}