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sqlhelper

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Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/-->using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Collections;

namespace SystemDAO
{
    /// <summary>
    /// 数据库的通用访问代码 苏飞修改
    /// 
    /// 此类为抽象类,
    /// 不允许实例化,在应用时直接调用即可
    /// </summary>
    public abstract class SqlHelper
    {
        /// <summary>
        /// 数据库连接字符串
        /// </summary>

        public static readonly string connectionString = System.Configuration.ConfigurationSettings.AppSettings["con"].ToString().Trim();
        // Hashtable to store cached parameters
        private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());

        #region//ExecteNonQuery方法

        /// <summary>
        ///执行一个不需要返回值的SqlCommand命令,通过指定专用的连接字符串。
        /// 使用参数数组形式提供参数列表 
        /// </summary>
        /// <param name="connectionString">一个有效的数据库连接字符串</param>
        /// <param name="cmdType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回一个数值表示此SqlCommand命令执行后影响的行数</returns>
        public static int ExecteNonQuery(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                //通过PrePareCommand方法将参数逐个加入到SqlCommand的参数集合中
                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
                int val = cmd.ExecuteNonQuery();
                //清空SqlCommand中的参数列表
                cmd.Parameters.Clear();
                return val;
            }
        }

        /// <summary>
        ///执行一个不需要返回值的SqlCommand命令,通过指定专用的连接字符串。
        /// 使用参数数组形式提供参数列表 
        /// </summary>
        /// <param name="cmdType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回一个数值表示此SqlCommand命令执行后影响的行数</returns>
        public static int ExecteNonQuery(CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecteNonQuery(connectionString ,cmdType, cmdText, commandParameters);
        }

        /// <summary>
        ///存储过程专用
        /// </summary>
        /// <param name="cmdText">存储过程的名字</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回一个数值表示此SqlCommand命令执行后影响的行数</returns>
        public static int ExecteNonQueryProducts(string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecteNonQuery(CommandType.StoredProcedure, cmdText, commandParameters);
        }

        /// <summary>
        ///Sql语句专用
        /// </summary>
        /// <param name="cmdText">T_Sql语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回一个数值表示此SqlCommand命令执行后影响的行数</returns>
        public static int ExecteNonQueryText(string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecteNonQuery(CommandType.Text, cmdText, commandParameters);
        }

        #endregion
        #region//GetTable方法

        /// <summary>
        /// 执行一条返回结果集的SqlCommand,通过一个已经存在的数据库连接
        /// 使用参数数组提供参数
        /// </summary>
        /// <param name="connecttionString">一个现有的数据库连接</param>
        /// <param name="cmdTye">SqlCommand命令类型</param>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回一个表集合(DataTableCollection)表示查询得到的数据集</returns>
        public static DataTableCollection GetTable(string connecttionString, CommandType cmdTye, string cmdText, SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            DataSet ds = new DataSet();
            using (SqlConnection conn = new SqlConnection(connecttionString))
            {
                PrepareCommand(cmd, conn, null, cmdTye, cmdText, commandParameters);
                SqlDataAdapter adapter = new SqlDataAdapter();
                adapter.SelectCommand = cmd;
                adapter.Fill(ds);
            }
            DataTableCollection table = ds.Tables;
            return table;
        }

        /// <summary>
        /// 执行一条返回结果集的SqlCommand,通过一个已经存在的数据库连接
        /// 使用参数数组提供参数
        /// </summary>
        /// <param name="cmdTye">SqlCommand命令类型</param>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回一个表集合(DataTableCollection)表示查询得到的数据集</returns>
        public static DataTableCollection GetTable(CommandType cmdTye, string cmdText, SqlParameter[] commandParameters)
        {
            return GetTable(cmdTye, cmdText, commandParameters);
        }


        /// <summary>
        /// 存储过程专用
        /// </summary>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回一个表集合(DataTableCollection)表示查询得到的数据集</returns>
        public static DataTableCollection GetTableProducts(string cmdText, SqlParameter[] commandParameters)
        {
            return GetTable(CommandType.StoredProcedure, cmdText, commandParameters);
        }

        /// <summary>
        /// Sql语句专用
        /// </summary>
        /// <param name="cmdText"> T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回一个表集合(DataTableCollection)表示查询得到的数据集</returns>
        public static DataTableCollection GetTableText(string cmdText, SqlParameter[] commandParameters)
        {
            return GetTable(CommandType.Text, cmdText, commandParameters);
        }
        #endregion


        /// <summary>
        /// 为执行命令准备参数
        /// </summary>
        /// <param name="cmd">SqlCommand 命令</param>
        /// <param name="conn">已经存在的数据库连接</param>
        /// <param name="trans">数据库事物处理</param>
        /// <param name="cmdType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
        /// <param name="cmdText">Command text,T-SQL语句 例如 Select * from Products</param>
        /// <param name="cmdParms">返回带参数的命令</param>
        private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, CommandType cmdType, string cmdText, SqlParameter[] cmdParms)
        {
            //判断数据库连接状态
            if (conn.State != ConnectionState.Open)
                conn.Open();
            cmd.Connection = conn;
            cmd.CommandText = cmdText;
            //判断是否需要事物处理
            if (trans != null)
                cmd.Transaction = trans;
            cmd.CommandType = cmdType;
            if (cmdParms != null)
            {
                foreach (SqlParameter parm in cmdParms)
                    cmd.Parameters.Add(parm);
            }
        }

        /// <summary>
        /// Execute a SqlCommand that returns a resultset against the database specified in the connection string 
        /// using the provided parameters.
        /// </summary>
        /// <param name="connectionString">一个有效的数据库连接字符串</param>
        /// <param name="cmdType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>A SqlDataReader containing the results</returns>
        public static SqlDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            SqlConnection conn = new SqlConnection(connectionString);
            // we use a try/catch here because if the method throws an exception we want to 
            // close the connection throw code, because no datareader will exist, hence the 
            // commandBehaviour.CloseConnection will not work
            try
            {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
                SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                cmd.Parameters.Clear();
                return rdr;
            }
            catch
            {
                conn.Close();
                throw;
            }
        }
        #region//ExecuteDataSet方法

        /// <summary>
        /// return a dataset
        /// </summary>
        /// <param name="connectionString">一个有效的数据库连接字符串</param>
        /// <param name="cmdType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>return a dataset</returns>
        public static DataSet ExecuteDataSet(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlConnection conn = new SqlConnection(connectionString);
            SqlCommand cmd = new SqlCommand();
            try
            {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
                SqlDataAdapter da = new SqlDataAdapter();
                DataSet ds = new DataSet();
                da.SelectCommand = cmd;
                da.Fill(ds);
                return ds;
            }
            catch
            {
                conn.Close();
                throw;
            }
        }


        /// <summary>
        /// 返回一个DataSet
        /// </summary>
        /// <param name="cmdType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>return a dataset</returns>
        public static DataSet ExecuteDataSet(CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecuteDataSet(connectionString, cmdType, cmdText, commandParameters);
        }

        /// <summary>
        /// 返回一个DataSet
        /// </summary>
        /// <param name="cmdText">存储过程的名字</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>return a dataset</returns>
        public static DataSet ExecuteDataSetProducts(string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecuteDataSet(connectionString, CommandType.StoredProcedure, cmdText, commandParameters);
        }

        /// <summary>
        /// 返回一个DataSet
        /// </summary>

        /// <param name="cmdText">T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>return a dataset</returns>
        public static DataSet ExecuteDataSetText(string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecuteDataSet(connectionString, CommandType.Text, cmdText, commandParameters);
        }


        public static DataView ExecuteDataSet(string connectionString, string sortExpression, string direction, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlConnection conn = new SqlConnection(connectionString);
            SqlCommand cmd = new SqlCommand();
            try
            {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
                SqlDataAdapter da = new SqlDataAdapter();
                DataSet ds = new DataSet();
                da.SelectCommand = cmd;
                da.Fill(ds);
                DataView dv = ds.Tables[0].DefaultView;
                dv.Sort = sortExpression + " " + direction;
                return dv;
            }
            catch
            {
                conn.Close();
                throw;
            }
        }
        #endregion


        #region // ExecuteScalar方法


        /// <summary>
        /// 返回第一行的第一列
        /// </summary>
        /// <param name="cmdType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回一个对象</returns>
        public static object ExecuteScalar(CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecuteScalar(SqlHelper.connectionString, cmdType, cmdText, commandParameters);
        }

        /// <summary>
        /// 返回第一行的第一列存储过程专用
        /// </summary>
        /// <param name="cmdText">存储过程的名字</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回一个对象</returns>
        public static object ExecuteScalarProducts(string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecuteScalar(SqlHelper.connectionString, CommandType.StoredProcedure, cmdText, commandParameters);
        }

        /// <summary>
        /// 返回第一行的第一列Sql语句专用
        /// </summary>
        /// <param name="cmdText">者 T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回一个对象</returns>
        public static object ExecuteScalarText(string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecuteScalar(SqlHelper.connectionString, CommandType.Text, cmdText, commandParameters);
        }

        /// <summary>
        /// Execute a SqlCommand that returns the first column of the first record against the database specified in the connection string 
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
        /// </remarks>
        /// <param name="connectionString">一个有效的数据库连接字符串</param>
        /// <param name="cmdType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>An object that should be converted to the expected type using Convert.To{Type}</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>
        /// Execute a SqlCommand that returns the first column of the first record against an existing database connection 
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
        /// </remarks>
        /// <param name="connectionString">一个有效的数据库连接字符串</param>
        /// <param name="cmdType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>An object that should be converted to the expected type using Convert.To{Type}</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


        /// <summary>
        /// add parameter array to the cache
        /// </summary>
        /// <param name="cacheKey">Key to the parameter cache</param>
        /// <param name="cmdParms">an array of SqlParamters to be cached</param>
        public static void CacheParameters(string cacheKey, params SqlParameter[] commandParameters)
        {
            parmCache[cacheKey] = commandParameters;
        }

        /// <summary>
        /// Retrieve cached parameters
        /// </summary>
        /// <param name="cacheKey">key used to lookup parameters</param>
        /// <returns>Cached SqlParamters array</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;
        }


        /// <summary>
        /// 检查是否存在
        /// </summary>
        /// <param name="strSql">Sql语句</param>
        /// <returns>bool结果</returns>
        public static bool Exists(string strSql)
        {
            int cmdresult = Convert.ToInt32(ExecuteScalar(connectionString, CommandType.Text, strSql, null));
            if (cmdresult == 0)
            {
                return false;
            }
            else
            {
                return true;
            }
        }

        /// <summary>
        /// 检查是否存在
        /// </summary>
        /// <param name="strSql">Sql语句</param>
        /// <param name="cmdParms">参数</param>
        /// <returns>bool结果</returns>
        public static bool Exists(string strSql, params SqlParameter[] cmdParms)
        {
            int cmdresult = Convert.ToInt32(ExecuteScalar(connectionString, CommandType.Text, strSql, cmdParms));
            if (cmdresult == 0)
            {
                return false;
            }
            else
            {
                return true;
            }
        }
    }

}

 

 

 

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Collections;
using System.Data.SqlClient;
 
/// <summary>
/// 数据库的通用访问代码
/// 此类为抽象类,不允许实例化,在应用时直接调用即可
/// </summary>
public abstract class SqlHelper
{
    //获取数据库连接字符串,其属于静态变量且只读,项目中所有文档可以直接使用,但不能修改
    public static readonly string ConnectionStringLocalTransaction = ConfigurationManager.ConnectionStrings["pubsConnectionString"].ConnectionString;
 
    // 哈希表用来存储缓存的参数信息,哈希表可以存储任意类型的参数。
    private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());
 
    /// <summary>
    ///执行一个不需要返回值的SqlCommand命令,通过指定专用的连接字符串。
    /// 使用参数数组形式提供参数列表 
    /// </summary>
    /// <remarks>
    /// 使用示例:
    ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
    /// </remarks>
    /// <param name="connectionString">一个有效的数据库连接字符串</param>
    /// <param name="commandType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
    /// <param name="commandText">存储过程的名字或者 T-SQL 语句</param>
    /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
    /// <returns>返回一个数值表示此SqlCommand命令执行后影响的行数</returns>
    public static int ExecuteNonQuery(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
    {
 
        SqlCommand cmd = new SqlCommand();
 
        using (SqlConnection conn = new SqlConnection(connectionString))
        {
            //通过PrePareCommand方法将参数逐个加入到SqlCommand的参数集合中
            PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
            int val = cmd.ExecuteNonQuery();
 
            //清空SqlCommand中的参数列表
            cmd.Parameters.Clear();
            return val;
        }
    }
     
    /// <summary>
    ///执行一条不返回结果的SqlCommand,通过一个已经存在的数据库连接 
    /// 使用参数数组提供参数
    /// </summary>
    /// <remarks>
    /// 使用示例:  
    ///  int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
    /// </remarks>
    /// <param name="conn">一个现有的数据库连接</param>
    /// <param name="commandType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
    /// <param name="commandText">存储过程的名字或者 T-SQL 语句</param>
    /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
    /// <returns>返回一个数值表示此SqlCommand命令执行后影响的行数</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>
    /// 执行一条不返回结果的SqlCommand,通过一个已经存在的数据库事物处理 
    /// 使用参数数组提供参数
    /// </summary>
    /// <remarks>
    /// 使用示例: 
    ///  int result = ExecuteNonQuery(trans, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
    /// </remarks>
    /// <param name="trans">一个存在的 sql 事物处理</param>
    /// <param name="commandType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
    /// <param name="commandText">存储过程的名字或者 T-SQL 语句</param>
    /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
    /// <returns>返回一个数值表示此SqlCommand命令执行后影响的行数</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;
    }
 
    /// <summary>
    /// 执行一条返回结果集的SqlCommand命令,通过专用的连接字符串。
    /// 使用参数数组提供参数
    /// </summary>
    /// <remarks>
    /// 使用示例:  
    ///  SqlDataReader r = ExecuteReader(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
    /// </remarks>
    /// <param name="connectionString">一个有效的数据库连接字符串</param>
    /// <param name="commandType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
    /// <param name="commandText">存储过程的名字或者 T-SQL 语句</param>
    /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
    /// <returns>返回一个包含结果的SqlDataReader</returns>
    public static SqlDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
    {
        SqlCommand cmd = new SqlCommand();
        SqlConnection conn = new SqlConnection(connectionString);
 
        // 在这里使用try/catch处理是因为如果方法出现异常,则SqlDataReader就不存在,
        //CommandBehavior.CloseConnection的语句就不会执行,触发的异常由catch捕获。
        //关闭数据库连接,并通过throw再次引发捕捉到的异常。
        try
        {
            PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
            SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
            cmd.Parameters.Clear();
            return rdr;
        }
        catch
        {
            conn.Close();
            throw;
        }
    }
 
    /// <summary>
    /// 执行一条返回第一条记录第一列的SqlCommand命令,通过专用的连接字符串。 
    /// 使用参数数组提供参数
    /// </summary>
    /// <remarks>
    /// 使用示例:  
    ///  Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
    /// </remarks>
    /// <param name="connectionString">一个有效的数据库连接字符串</param>
    /// <param name="commandType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
    /// <param name="commandText">存储过程的名字或者 T-SQL 语句</param>
    /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
    /// <returns>返回一个object类型的数据,可以通过 Convert.To{Type}方法转换类型</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>
    /// 执行一条返回第一条记录第一列的SqlCommand命令,通过已经存在的数据库连接。
    /// 使用参数数组提供参数
    /// </summary>
    /// <remarks>
    /// 使用示例: 
    ///  Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
    /// </remarks>
    /// <param name="conn">一个已经存在的数据库连接</param>
    /// <param name="commandType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
    /// <param name="commandText">存储过程的名字或者 T-SQL 语句</param>
    /// <param name="commandParameters">以数组形式提供SqlCommand命令中用到的参数列表</param>
    /// <returns>返回一个object类型的数据,可以通过 Convert.To{Type}方法转换类型</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;
    }
 
    /// <summary>
    /// 缓存参数数组
    /// </summary>
    /// <param name="cacheKey">参数缓存的键值</param>
    /// <param name="cmdParms">被缓存的参数列表</param>
    public static void CacheParameters(string cacheKey, params SqlParameter[] commandParameters)
    {
        parmCache[cacheKey] = commandParameters;
    }
 
    /// <summary>
    /// 获取被缓存的参数
    /// </summary>
    /// <param name="cacheKey">用于查找参数的KEY值</param>
    /// <returns>返回缓存的参数数组</returns>
    public static SqlParameter[] GetCachedParameters(string cacheKey)
    {
        SqlParameter[] cachedParms = (SqlParameter[])parmCache[cacheKey];
 
        if (cachedParms == null)
            return null;
 
        //新建一个参数的克隆列表
        SqlParameter[] clonedParms = new SqlParameter[cachedParms.Length];
 
        //通过循环为克隆参数列表赋值
        for (int i = 0, j = cachedParms.Length; i < j; i++)
            //使用clone方法复制参数列表中的参数
            clonedParms[i] = (SqlParameter)((ICloneable)cachedParms[i]).Clone();
 
        return clonedParms;
    }
 
    /// <summary>
    /// 为执行命令准备参数
    /// </summary>
    /// <param name="cmd">SqlCommand 命令</param>
    /// <param name="conn">已经存在的数据库连接</param>
    /// <param name="trans">数据库事物处理</param>
    /// <param name="cmdType">SqlCommand命令类型 (存储过程, T-SQL语句, 等等。)</param>
    /// <param name="cmdText">Command text,T-SQL语句 例如 Select * from Products</param>
    /// <param name="cmdParms">返回带参数的命令</param>
    private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, CommandType cmdType, string cmdText, SqlParameter[] cmdParms)
    {
 
        //判断数据库连接状态
        if (conn.State != ConnectionState.Open)
            conn.Open();
 
        cmd.Connection = conn;
        cmd.CommandText = cmdText;
 
        //判断是否需要事物处理
        if (trans != null)
            cmd.Transaction = trans;
 
        cmd.CommandType = cmdType;
 
        if (cmdParms != null)
        {
            foreach (SqlParameter parm in cmdParms)
                cmd.Parameters.Add(parm);
        }
    }
} 

 

sqlhelper

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原文地址:http://www.cnblogs.com/hetuan/p/4703864.html

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