1  public static class  SqlHelper 2     { 3         public static readonly string connstr = 4             ConfigurationManager.ConnectionStrings["connstr"].ConnectionString; 5  6         public static SqlConnection OpenConnection() 7         { 8             SqlConnection conn = new SqlConnection(connstr); 9             conn.Open();10             return conn;11         }12 13         public static int ExecuteNonQuery(string cmdText,14             params SqlParameter[] parameters)15         {16             using (SqlConnection conn = new SqlConnection(connstr))17             {18                 conn.Open();19                 return ExecuteNonQuery(conn, cmdText, parameters);20             }21         }22 23         public static object ExecuteScalar(string cmdText,24             params SqlParameter[] parameters)25         {26             using (SqlConnection conn = new SqlConnection(connstr))27             {28                 conn.Open();29                 return ExecuteScalar(conn, cmdText, parameters);30             }31         }32 33         public static DataTable ExecuteDataTable(string cmdText,34             params SqlParameter[] parameters)35         {36             using (SqlConnection conn = new SqlConnection(connstr))37             {38                 conn.Open();39                 return ExecuteDataTable(conn, cmdText, parameters);40             }41         }42 43         public static int ExecuteNonQuery(SqlConnection conn,string cmdText,44            params SqlParameter[] parameters)45         {46             using (SqlCommand cmd = conn.CreateCommand())47             {48                 cmd.CommandText = cmdText;49                 cmd.Parameters.AddRange(parameters);50                 return cmd.ExecuteNonQuery();51             }52         }53 54         public static object ExecuteScalar(SqlConnection conn, string cmdText,55             params SqlParameter[] parameters)56         {57             using (SqlCommand cmd = conn.CreateCommand())58             {59                 cmd.CommandText = cmdText;60                 cmd.Parameters.AddRange(parameters);61                 return cmd.ExecuteScalar();62             }63         }64 65         public static DataTable ExecuteDataTable(SqlConnection conn, string cmdText,66             params SqlParameter[] parameters)67         {68             using (SqlCommand cmd = conn.CreateCommand())69             {70                 cmd.CommandText = cmdText;71                 cmd.Parameters.AddRange(parameters);72                 using (SqlDataAdapter adapter = new SqlDataAdapter(cmd))73                 {74                     DataTable dt = new DataTable();75                     adapter.Fill(dt);76                     return dt;77                 }78             }79         }80 81         public static object ToDBValue(this object value)82         {83             return value == null ? DBNull.Value : value;84         }85 86         public static object FromDBValue(this object dbValue)87         {88             return dbValue == DBNull.Value ? null : dbValue;89         }90     }