自己写的访问SqlServer数据库的通用DAL层

如题,直接贴代码.

首先是DataTable转List<T>的方法,这个方法通用性极强.

         #region Table转List
         /// <summary>
         /// Table转List
         /// </summary>
         /// <typeparam name="T"></typeparam>
         /// <param name="dt"></param>
         /// <returns></returns>
         public static List<T> TableToList<T>(DataTable dt) where T : new()
         {
             // 定义集合
             IList<T> list = new List<T>();

             // 获得此模型的类型
             Type type = typeof(T);

             foreach (DataRow dr in dt.Rows)
             {
                 T t = new T();

                 // 获得公共属性
                 PropertyInfo[] propertys = t.GetType().GetProperties();

                 foreach (PropertyInfo pi in propertys)
                 {
                     // 判断此属性是否有Setter
                     if (!pi.CanWrite) continue;

                     object value = dr[pi.Name];
                     if (value != DBNull.Value)
                         pi.SetValue(t, value, null);
                 }

                 list.Add(t);
             }
             return list.ToList();
         }
         #endregion

下面贴出主要代码

     /// <summary>
     /// 数据访问基类:BaseService
     /// </summary>
     /// <typeparam name="T"></typeparam>
     public class BaseService<T> : IBaseService<T> where T : class ,new()
     {
         /// <summary>
         /// 得到某列最大值
         /// </summary>
         /// <param name="connection"></param>
         /// <param name="fieldname"></param>
         /// <returns></returns>
         public virtual int GetMax(string connection,string fieldname)
         {
             #region 参数
             T entity = new T();
             SqlParameter[] parameters = new SqlParameter[]
             {
                 new SqlParameter("@fieldname",fieldname)
             };
             #endregion

             StringBuilder sqlStr=new StringBuilder();
             sqlStr.Append("select max(");
             sqlStr.Append("@fieldname");
             sqlStr.Append(") from ");
             sqlStr.Append(entity.GetType().Name);

             return int.Parse(DatabaseAccess.SqlHelper.ExecuteDataSetText(connection, sqlStr.ToString(), parameters).Tables[].Rows[][].ToString());
         }

         /// <summary>
         /// 是否存在该记录
         /// </summary>
         /// <param name="connection">连接字符串</param>
         /// <param name="primarykey">主键值</param>
         /// <returns></returns>
         public virtual bool Exists(string connection, object primarykey)
         {
             #region 参数
             T entity = new T();

             string primaryKey = GetPrimarykey(connection, entity);
             List<SqlParameter> parameters = new List<SqlParameter>();
             parameters.Add(new SqlParameter("@" + primaryKey, primarykey));
             #endregion

             StringBuilder sqlStr = new StringBuilder();
             sqlStr.Append("select count(1) from ");
             sqlStr.Append(entity.GetType().Name);
             sqlStr.Append(" where ");
             sqlStr.Append(primaryKey + "=@" + primaryKey);

             int res = DatabaseAccess.SqlHelper.ExecteNonQueryText(connection, sqlStr.ToString(), parameters.ToArray());
             if (res > )
                 return true;
             else
                 return false;
         }

         /// <summary>
         /// 增加一条数据
         /// </summary>
         public virtual bool Add(string connection, T entity)
         {
             #region 参数
             List<SqlParameter> parameters = new List<SqlParameter>();
             string fields = "";
             string placeholders = "";
             foreach (var item in entity.GetType().GetProperties())
             {
                 fields += item.Name + ",";
                 placeholders += "@" + item.Name + ",";

                 SqlParameter parameter = new SqlParameter();
                 parameter.ParameterName = "@" + item.Name;
                 parameter.Value = item.GetValue(entity, null);
                 parameters.Add(parameter);
             }
             #endregion

             StringBuilder sqlStr = new StringBuilder();
             sqlStr.Append("insert " + entity.GetType().Name + " (");
             sqlStr.Append(fields.Substring(, fields.Length - ) + ")");
             sqlStr.Append(" values (");
             sqlStr.Append(placeholders.Substring(, placeholders.Length - ) + ")");

             int res = DatabaseAccess.SqlHelper.ExecteNonQueryText(connection, sqlStr.ToString(), parameters.ToArray());
             if (res > )
                 return true;
             else
                 return false;
         }

         /// <summary>
         /// 更新一条数据
         /// </summary>
         /// <param name="connection">连接字符串</param>
         /// <param name="entity">类</param>
         /// <returns></returns>
         public virtual bool Update(string connection, T entity)
         {
             #region 参数
             string primaryKey = GetPrimarykey(connection, entity);
             List<SqlParameter> parameters = new List<SqlParameter>();
             parameters.Add(new SqlParameter("@"+primaryKey, entity.GetType().GetProperty(primaryKey).GetValue(entity,null)));
             string fields = "";
             foreach (var item in entity.GetType().GetProperties())
             {
                 if (item.Name != primaryKey)
                 {
                     fields += item.Name + "=@" + item.Name + ",";

                     SqlParameter parameter = new SqlParameter();
                     parameter.ParameterName = "@" + item.Name;
                     parameter.Value = item.GetValue(entity, null);
                     parameters.Add(parameter);
                 }
             }
             #endregion

             StringBuilder sqlStr = new StringBuilder();
             sqlStr.Append("update " + entity.GetType().Name);
             sqlStr.Append(" set ");
             sqlStr.Append(fields.Substring(,fields.Length-));
             sqlStr.Append(" where ");
             sqlStr.Append(primaryKey + "=@" + primaryKey);

             int res = DatabaseAccess.SqlHelper.ExecteNonQueryText(connection, sqlStr.ToString(), parameters.ToArray());
             if (res > )
                 return true;
             else
                 return false;
         }

         /// <summary>
         /// 删除一条数据
         /// </summary>
         /// <param name="connection">连接字符串</param>
         /// <param name="primaryKey">主键值</param>
         /// <returns></returns>
         public virtual bool Delete(string connection, object primarykey)
         {
             #region 参数
             T entity = new T();

             string primaryKey = GetPrimarykey(connection, entity);
             List<SqlParameter> parameters = new List<SqlParameter>();
             parameters.Add(new SqlParameter("@" + primaryKey, primarykey));
             #endregion

             StringBuilder sqlStr = new StringBuilder();
             sqlStr.Append("delete from ");
             sqlStr.Append(entity.GetType().Name);
             sqlStr.Append(" where ");
             sqlStr.Append(primaryKey + "=@" + primaryKey);

             int res = DatabaseAccess.SqlHelper.ExecteNonQueryText(connection, sqlStr.ToString(), parameters.ToArray());
             if (res > )
                 return true;
             else
                 return false;
         }

         /// <summary>
         /// 删除多条数据
         /// </summary>
         /// <param name="connection">连接字符串</param>
         /// <param name="base_idlist">主键值列表</param>
         /// <returns></returns>
         public virtual bool DeleteList(string connection, List<object> primarykeys)
         {
             #region 参数
             T entity = new T();

             string primaryKey = GetPrimarykey(connection, entity);

             string primaryKeys = "";
             foreach(var item in primarykeys)
             {
                 primaryKeys += item.ToString();
             }

             List<SqlParameter> parameters = new List<SqlParameter>();
             parameters.Add(new SqlParameter("@" + primaryKey, primaryKeys));
             #endregion

             StringBuilder sqlStr = new StringBuilder();
             sqlStr.Append("delete from ");
             sqlStr.Append(entity.GetType().Name);
             sqlStr.Append(" where ");
             sqlStr.Append(primaryKey + " in(@" + primaryKey + ")");

             int res = DatabaseAccess.SqlHelper.ExecteNonQueryText(connection, sqlStr.ToString(), parameters.ToArray());
             if (res > )
                 return true;
             else
                 return false;
         }

         /// <summary>
         /// 得到一个对象实体
         /// </summary>
         /// <param name="connection">连接字符串</param>
         /// <param name="primarykey">主键值</param>
         /// <returns></returns>
         public virtual T GetModel(string connection, object primarykey)
         {
             #region 参数
             T entity = new T();

             string primaryKey = GetPrimarykey(connection, entity);

             List<SqlParameter> parameters = new List<SqlParameter>();
             parameters.Add(new SqlParameter("@table", entity.GetType().Name));
             parameters.Add(new SqlParameter("@" + primaryKey, primarykey));
             #endregion

             StringBuilder sqlStr = new StringBuilder();
             sqlStr.Append("select * from ");
             sqlStr.Append(entity.GetType().Name);
             sqlStr.Append(" where ");
             sqlStr.Append(primaryKey + "=@" + primaryKey);

             return Common.ToList.TableToList<T>(DatabaseAccess.SqlHelper.ExecuteDataSetText(connection, sqlStr.ToString(), parameters.ToArray()).Tables[]).FirstOrDefault();
         }

         /// <summary>
         /// 获得数据列表
         /// </summary>
         /// <param name="connection">连接字符串</param>
         /// <param name="strWhere">查询条件</param>
         /// <returns></returns>
         public virtual List<T> GetList(string connection, string strWhere)
         {
             #region 参数
             T entity = new T();

             List<SqlParameter> parameters = new List<SqlParameter>();
             parameters.Add(new SqlParameter("@where", strWhere));
             #endregion

             StringBuilder sqlStr = new StringBuilder();
             sqlStr.Append("select * from ");
             sqlStr.Append(entity.GetType().Name);
             if (strWhere.Trim().Length > )
                 sqlStr.Append(" where @where");

             return Common.ToList.TableToList<T>(DatabaseAccess.SqlHelper.ExecuteDataSetText(connection, sqlStr.ToString(), parameters.ToArray()).Tables[]);
         }

         /// <summary>
         /// 获得总数
         /// </summary>
         /// <param name="connection">连接字符串</param>
         /// <param name="strWhere">查询条件</param>
         /// <returns></returns>
         public virtual int GetRecordCount(string connection, string strWhere)
         {
             #region 参数
             T entity = new T();

             List<SqlParameter> parameters = new List<SqlParameter>();
             parameters.Add(new SqlParameter("@where", strWhere));
             #endregion

             StringBuilder sqlStr = new StringBuilder();
             sqlStr.Append("select count(1) FROM ");
             sqlStr.Append(entity.GetType().Name);
             if (strWhere.Trim().Length > )
                 sqlStr.Append(" where @where");

             return int.Parse(DatabaseAccess.SqlHelper.ExecuteScalarText(connection, sqlStr.ToString(), parameters.ToArray()).ToString());
         }

         /// <summary>
         /// 执行sql语句
         /// </summary>
         /// <param name="connection"></param>
         /// <param name="cmdtype"></param>
         /// <param name="sql"></param>
         /// <param name="parameters"></param>
         /// <returns></returns>
         public virtual int ExecteNonQuerySQL(string connection, CommandType cmdtype, string sql, params SqlParameter[] parameters)
         {
             return DatabaseAccess.SqlHelper.ExecteNonQuery(connection, cmdtype, sql, parameters);
         }

         /// <summary>
         /// 获取类主键
         /// </summary>
         /// <param name="connection">连接字符串</param>
         /// <param name="entity">类</param>
         /// <returns></returns>
         public virtual string GetPrimarykey(string connection, T entity)
         {
             StringBuilder sqlStr = new StringBuilder();
             sqlStr.Append("EXEC sp_pkeys @table_name='" + entity.GetType().Name + "'");

             SqlParameter[] parameters = new SqlParameter[]
             {

             };

             return DatabaseAccess.SqlHelper.ExecuteDataSetText(connection,sqlStr.ToString(),parameters).Tables[].Rows[]["COLUMN_NAME"].ToString();
         }

         /// <summary>
         /// 执行sql语句
         /// </summary>
         /// <param name="connection"></param>
         /// <param name="cmdtype"></param>
         /// <param name="sql"></param>
         /// <param name="parameters"></param>
         /// <returns></returns>
         public virtual DataSet ExecuteDataSetSQL(string connection, CommandType cmdtype, string sql, params SqlParameter[] parameters)
         {
             return DatabaseAccess.SqlHelper.ExecuteDataSet(connection, cmdtype, sql, parameters);
         }
     }

这些方法中默认表都是有主键的,而且实体名称和表名一致,否则执行会报错.

这套方法已经被我用在一个旧项目的改造中,目前来看效果还是不错的,因此在这与大家分享,因为本人水平有限,而且没用太多时间去完善,这套代码肯定会有很多瑕疵,希望高手不吝赐教.