sqlhelper简化版

public class sqlhelper
    {
        /// <summary>
        /// The SqlHelper class is intended to encapsulate high performance, scalable best practices for 
        /// common uses of SqlClient
        /// </summary>
        public sealed class SqlHelper
        {
            //获取数据库连接字符串，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["stdInfoConnectionString"].ConnectionString;

            /// <summary>
            /// 执行一个不需要返回值的sqlCommand命了，通过制定专用的连接字符串
            /// 使用参数数组形式提供参数
            /// </summary>
            /// <remarks>
            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();
                    cmd.Parameters.Clear();
                    return val;
                }
            }

            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;
                }
            }
            public static object ExecuteScalar(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);
                    object val = cmd.ExecuteScalar();
                    cmd.Parameters.Clear();
                    return val;

                }
            }
            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;

                //判断事务是否需要处理
                if (trans != null)
                    cmd.Transaction = trans;

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



            }
        }

    }