处女篇：自用C#后端SqlHelper.cs类

自用SqlHelper.cs类，此类来自软谋教育徐老师课程SqlHelper.cs！

 using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Configuration;
 using System.Data;
 using System.Data.SqlClient;
 using System.Linq;
 using System.Web;

 namespace PROJECT20160712
 {
     /// 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 = ConfigurationManager.ConnectionStrings["con"].ToString();
         // 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[].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 = , 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 == )
             {
                 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 == )
             {
                 return false;
             }
             else
             {
                 return true;
             }
         }
     }
 }