从基础学习 string.join(“,” keys.toarray())

public static int InsertModel<T>(T t) where T : BaseModel
      {
          Type type = typeof(T);
          string columnStrings = string.Join(",", type.GetProperties().Select(p => string.Format("[{0}]", p.Name)));
          string sql = "insert into "+type.Name+"(";
          foreach (var item in type.GetProperties())
          {
              if (item.Name != "Id")
              {
                  sql+=item.Name+",";
              }
          }
          sql = sql.Substring(0, sql.Length - 1);
          sql += ")";
          sql+=" values(";
          foreach (var item in type.GetProperties())
          {
              if (item.Name != "Id")
              {
                  sql += "'" + item.GetValue(t) + "',";
              }
          }
          sql = sql.Substring(0, sql.Length - 1);
          sql += ")";
          return DbHelperSQL.ExecuteSql(sql);

      }

public bool Insert<T>(T t) where T : BaseModel
      {
          //插入实体时要判断一下时间的插入.还可以通过特性来判断一下数据的长度
          //约定的id为自增长.
          var type = typeof(T);
          var keys = new List<string>();
          var values = new List<string>();
          var par = new List<SqlParameter>();
          foreach (var item in type.GetProperties())
          {
              var value = item.GetValue(t);
              if (item.Name.ToLower() == "id") continue;
              keys.Add(item.Name);
              values.Add("@" + item.Name);
              par.Add(new SqlParameter("@" + item.Name, value));
          }
          var c = string.Join(",", keys.ToArray());
          var v = string.Join(",", values.ToArray());
          var sql = string.Format($"INSERT INTO [{type.Name}] ({c}) " +
              $"VALUES({v})");

          return ExcuteSql<bool>(sql, cmd =>
          {
              foreach (var parameter in par)
                  cmd.Parameters.Add(parameter);

              var result = cmd.ExecuteNonQuery();
              return result > 0;
          });

          //   return RunCmd(sql, par.ToArray());
      }