SqlHelper模板

在实际开发中，我们不会直接使用拼写SQL语句的方法进行数据库操作，而是使用参数化的方法进行数据库操作，这样做的好处很多，不仅提高了程序的健壮性，同时也避免的SQL注入的问题。在这里，笔者为初学者提供一个SQLHelper模板，希望对新手有所启发。

 public static class SqlHelper
 {
     public static readonly string strConn = ConfigurationManager.ConnectionStrings["strConn"].ConnectionString;

     public static int ExecuteNonQuery(string cmdText, params SqlParameter[] parameters)
     {
         using (SqlConnection conn = new SqlConnection(strConn))
         {
             conn.Open();
             return ExecuteNonQuery(conn, cmdText, parameters);
         }
     }
     public static int ExecuteNonQuery(SqlConnection conn, string cmdText, params SqlParameter[] parameters)
     {
         using (SqlCommand cmd = conn.CreateCommand())
         {
             cmd.CommandText = cmdText;
             cmd.Parameters.AddRange(parameters);
             return cmd.ExecuteNonQuery();
         }
     }

     public static object ExecuteScalar(string cmdText, params SqlParameter[] parameters)
     {
         using (SqlConnection conn = new SqlConnection(strConn))
         {
             conn.Open();
             return ExecuteScalar(conn, cmdText, parameters);
         }
     }
     public static object ExecuteScalar(SqlConnection conn, string cmdText, params SqlParameter[] parameters)
     {
         using (SqlCommand cmd = conn.CreateCommand())
         {
             cmd.CommandText = cmdText;
             cmd.Parameters.AddRange(parameters);
             return cmd.ExecuteScalar();
         }
     }

     public static DataTable ExecuteDataTable(string cmdText, params SqlParameter[] parameters)
     {
         using (SqlConnection conn = new SqlConnection(strConn))
         {
             conn.Open();
             return ExecuteDataTable(conn, cmdText, parameters);
         }
     }
     public static DataTable ExecuteDataTable(SqlConnection conn, string cmdText, params SqlParameter[] parameters)
     {
         using (SqlCommand cmd = conn.CreateCommand())
         {
             cmd.CommandText = cmdText;
             cmd.Parameters.AddRange(parameters);
             using (SqlDataAdapter adapter = new SqlDataAdapter(cmd))
             {
                 DataTable dt = new DataTable();
                 adapter.Fill(dt);
                 return dt;
             }
         }
     }

     /// <summary>
     /// 存数据时防止为空
     /// </summary>
     /// <param name="value"></param>
     /// <returns></returns>
     public static object ToDbValue(this object value)
     {
         return value == null ? DBNull.Value : value;
     }

     /// <summary>
     /// 取数据时防止为空
     /// </summary>
     /// <param name="value"></param>
     /// <returns></returns>
     public static object FromDbValue(this object value)
     {
         return value == DBNull.Value ? null : value;
     }
 }