国产化中的 .NET Core 操作达梦数据库DM8的两种方式(操作详解)

目录

• 背景
• 环境
• SDK
• 操作数据库
• DbHelperSQL方式
• Dapper方式

背景

某个项目需要实现基础软件全部国产化，其中操作系统指定银河麒麟，数据库使用达梦V8，CPU平台的范围包括x64、龙芯、飞腾、鲲鹏等。考虑到这些基础产品对.NET的支持，最终选择了.NET Core 3.1。

环境

• CPU平台：x86-64 / Arm64
• 操作系统：银河麒麟 v4
• 数据库：DM8
• .NET：.NET Core 3.1

SDK

达梦自己提供了.NET操作其数据库的SDK，可以通过NuGet安装，也可以通过安装达梦数据库获取。因为NuGet上的版本不知道是谁提供的，所以这里以安装数据库获取相关SDK为例。

在官网下载DM8的数据库安装文件：https://www.dameng.com/list_103.html

下载前需要先登录，随便注册一个帐号就好了。

这里需要选择CPU和操作系统，按照你的开发环境选择即可，下载后按照提示安装。

这里以Windows10为例，安装后SDK文件的位置在：C:\dmdbms\drivers\dotNet

这里边有EF的SDK，也有NHibernate的SDK，不过这篇文章只使用最基础的基于ADO.NET的SDK。

这些SDK在文件夹DmProvider下边，这里还提供了一个Nuget包，可以放到自己的Nuget仓库中，方便内部安装。

可以看到，这个SDK可以支持.NET Core2.0以上的所有.NET版本。

操作数据库

这里提供两种方式：传统的DbHelperSQL方式 和 Dapper 方式。

DbHelperSQL方式

这种方式早年用的比较多，现在还有很多项目在使用，通过定义一组工具方法包装对数据库的各种增删改查操作。下面给出代码：

 public class DmDbClient
    {
        private string connectionString = string.Empty;

        /// <summary>
        /// 初始化DMClient的一个新实例
        /// </summary>
        /// <param name="str"></param>
        public DmDbClient(string str)
        {
            connectionString = str;
        }
        #region 通用快捷方法
        /// 执行一条SQL语句，确定记录是否存在
        /// <param name="sql">SQL查询语句</param>
        /// <returns></returns>
        public bool Exists(string sql)
            object obj = GetSingle(sql);
            int cmdresult;
            if (Equals(obj, null) || Equals(obj, DBNull.Value))
            {
                cmdresult = 0;
            }
            else
                cmdresult = int.Parse(obj.ToString());
            return cmdresult > 0;
        public async Task<bool> ExistsAsync(string sql)
            object obj = await GetSingleAsync(sql);
        /// <param name="paras">SQL参数数组</param>
        public bool Exists(string sql, params DmParameter[] paras)
            object obj = GetSingle(sql, paras);
            if ((object.Equals(obj, null)) || (object.Equals(obj, DBNull.Value)))
        public async Task<bool> ExistsAsync(string sql, params DmParameter[] paras)
            object obj = await GetSingleAsync(sql, paras);
        /// 获取记录条数
        /// <param name="tableName">表名</param>
        /// <param name="sqlCondition">查询条件</param>
        public int GetCount(string tableName, string sqlCondition)
            string sql = "select count(1) from `" + tableName + "`";
            if (!string.IsNullOrWhiteSpace(sqlCondition))
                sql += " where " + sqlCondition;
            object result = GetSingle(sql);
            if (result != null)
                return Convert.ToInt32(result);
                return 0;
        public async Task<int> GetCountAsync(string tableName, string sqlCondition)
            object result = await GetSingleAsync(sql);
        public int GetCount(string tableName, string sqlCondition, DmParameter[] paras)
            object result = GetSingle(sql, paras);
        public async Task<int> GetCountAsync(string tableName, string sqlCondition, DmParameter[] paras)
            object result = await GetSingleAsync(sql, paras);
        #endregion 通用快捷方法
        #region 执行简单SQL语句
        /// 执行SQL语句，返回影响的记录数
        /// <param name="sql">SQL语句</param>
        /// <returns>影响的记录数</returns>
        public int ExecuteSql(string sql)
            using (DmConnection connection = new DmConnection(connectionString))
                using (DmCommand cmd = new DmCommand(sql, connection))
                {
                    connection.Open();
                    int rows = cmd.ExecuteNonQuery();
                    return rows;
                }
        public async Task<int> ExecuteSqlAsync(string sql)
                    await connection.OpenAsync();
                    int rows = await cmd.ExecuteNonQueryAsync();
        /// 执行SQL语句，返回影响的记录数（可自定义超时时间）
        /// <param name="timeout">执行超时时间</param>
        public int ExecuteSqlByTime(string sql, int timeout)
            using (DmConnection connection = new DmConnection(this.connectionString))
                    cmd.CommandTimeout = timeout;
        public async Task<int> ExecuteSqlByTimeAsync(string sql, int timeout)
        /// 执行多条SQL语句，实现数据库事务。
        /// <param name="sqlList">多条SQL语句</param>
        public void ExecuteSqlTrans(ArrayList sqlList)
            using (DmConnection conn = new DmConnection(connectionString))
                conn.Open();
                using (DbTransaction trans = conn.BeginTransaction())
                    using (DmCommand cmd = new DmCommand())
                    {
                        cmd.Connection = conn;
                        cmd.Transaction = trans;
                        try
                        {
                            for (int n = 0; n < sqlList.Count; n++)
                            {
                                string sql = sqlList[n].ToString();
                                if (sql.Trim().Length > 1)
                                {
                                    cmd.CommandText = sql;
                                    cmd.ExecuteNonQuery();
                                }
                            }
                            trans.Commit();
                        }
                        catch (DmException ex)
                            trans.Rollback();
                            throw ex;
                    }
        public async Task ExecuteSqlTransAsync(ArrayList sqlList)
                await conn.OpenAsync();
                using (DbTransaction trans = await conn.BeginTransactionAsync())
                                    await cmd.ExecuteNonQueryAsync();
        /// 执行一条SQL查询语句，返回查询结果。
        /// <returns>查询结果</returns>
        public object GetSingle(string sql)
                    object obj = cmd.ExecuteScalar();
                    if ((object.Equals(obj, null)) || (object.Equals(obj, DBNull.Value)))
                        return null;
                    else
                        return obj;
        public async Task<object> GetSingleAsync(string sql)
                    object obj = await cmd.ExecuteScalarAsync();
        /// 执行查询语句，返回DbDataReader（切记要手工关闭DbDataReader）
        /// <param name="sql">查询语句</param>
        /// <returns>DmDataReader</returns>
        public DbDataReader ExecuteReader(string sql)
            DmConnection connection = new DmConnection(connectionString);
            DmCommand cmd = new DmCommand(sql, connection);
            connection.Open();
            return cmd.ExecuteReader();
        public async Task<DbDataReader> ExecuteReaderAsync(string sql)
            await connection.OpenAsync();
            return await cmd.ExecuteReaderAsync();
        /// 执行查询语句，返回DataSet
        /// <returns>DataSet</returns>
        public DataSet Query(string sql)
                using (DmDataAdapter command = new DmDataAdapter(sql, connection))
                    DataSet ds = new DataSet();
                    command.Fill(ds, "ds");
                    return ds;
        /// 执行查询语句，返回DataSet（可自定义超时时间）
        /// <param name="sql"></param>
        /// <param name="timeout"></param>
        public DataSet Query(string sql, int timeout)
                    command.SelectCommand.CommandTimeout = timeout;
        #endregion 执行简单SQL语句
        #region 执行带参数的SQL语句
        public int ExecuteSql(string sql, params DmParameter[] paras)
                using (DmCommand cmd = new DmCommand())
                    PrepareCommand(cmd, connection, null, sql, paras);
                    cmd.Parameters.Clear();
        public async Task<int> ExecuteSqlAsync(string sql, params DmParameter[] paras)
                    await PrepareCommandAsync(cmd, connection, null, sql, paras);
        /// 执行添加SQL语句，返回记录的ID（自动产生的自增主键）
        /// <param name="parms">SQL参数</param>
        /// <returns>记录的ID</returns>
        public int ExecuteAdd(string sql, params DmParameter[] parms)
            sql = sql + ";Select @@IDENTITY";
                    PrepareCommand(cmd, connection, null, sql, parms);
                    int recordID = Int32.Parse(cmd.ExecuteScalar().ToString());
                    return recordID;
        public async Task<int> ExecuteAddAsync(string sql, params DmParameter[] parms)
            sql = sql + ";select @@identity as newautoid";
                    await PrepareCommandAsync(cmd, connection, null, sql, parms);
                    int recordID;
                    try
                        recordID = int.Parse((await cmd.ExecuteScalarAsync()).ToString());
                    catch
                        recordID = -1;
        /// <param name="sqlList">SQL语句的哈希表（key为sql语句，value是该语句的DmParameter[]）</param>
        public void ExecuteSqlTrans(Hashtable sqlList)
                            foreach (DictionaryEntry entry in sqlList)
                                var sql = entry.Key.ToString();
                                var paras = (DmParameter[])entry.Value;
                                PrepareCommand(cmd, conn, trans, sql, paras);
                                int val = cmd.ExecuteNonQuery();
                                cmd.Parameters.Clear();
        public async Task ExecuteSqlTransAsync(Hashtable sqlList)
                                await PrepareCommandAsync(cmd, conn, trans, sql, paras);
                                int val = await cmd.ExecuteNonQueryAsync();
        /// 执行一条计算查询结果语句，返回查询结果。
        public object GetSingle(string sql, params DmParameter[] parms)
                    PrepareCommand(cmd, conn, null, sql, parms);
        public async Task<object> GetSingleAsync(string sql, params DmParameter[] parms)
                    await PrepareCommandAsync(cmd, conn, null, sql, parms);
        /// 执行查询语句，返回DmDataReader (切记要手工关闭DmDataReader)
        public DbDataReader ExecuteReader(string sql, params DmParameter[] parms)
            DmCommand cmd = new DmCommand();
            PrepareCommand(cmd, connection, null, sql, parms);
            DbDataReader myReader = cmd.ExecuteReader();
            cmd.Parameters.Clear();
            return myReader;
        public async Task<DbDataReader> ExecuteReaderAsync(string sql, params DmParameter[] parms)
            await PrepareCommandAsync(cmd, connection, null, sql, parms);
            var myReader = await cmd.ExecuteReaderAsync();
        /// <param name="paras">参数数组</param>
        public DataSet Query(string sql, params DmParameter[] paras)
                    using (DmDataAdapter da = new DmDataAdapter(cmd))
                        da.Fill(ds, "ds");
                        cmd.Parameters.Clear();
                        return ds;
        /// 准备SQL查询命令
        /// <param name="cmd">SQL命令对象</param>
        /// <param name="conn">SQL连接对象</param>
        /// <param name="trans">SQL事务对象</param>
        /// <param name="cmdText">SQL语句</param>
        private void PrepareCommand(DmCommand cmd, DmConnection conn, DbTransaction trans, string cmdText, DmParameter[] paras)
            if (conn.State != ConnectionState.Open)
            cmd.Connection = conn;
            cmd.CommandText = cmdText;
            if (trans != null)
                cmd.Transaction = trans;
            cmd.CommandType = CommandType.Text;
            if (paras != null)
                foreach (DmParameter parameter in paras)
                    if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) &&
                        (parameter.Value == null))
                        parameter.Value = DBNull.Value;
                    cmd.Parameters.Add(parameter);
        private async Task PrepareCommandAsync(DmCommand cmd, DmConnection conn, DbTransaction trans, string cmdText, DmParameter[] paras)
        #endregion 执行带参数的SQL语句
    }

使用方法也很简单，传入SQL语句和参数即可。这里给出几个增删改查的例子：

 public class PersonAdoNetDAL : IPersonDAL
    {
        static readonly DmDbClient _client = new DmDbClient("Server=127.0.0.1; UserId=TESTDB; PWD=1234567");

        public int Add(PersonModel model)
        {
            string sql = "insert into Person(Name,City) Values(:Name,:City)";
            DmParameter[] paras = new DmParameter[] {
                new DmParameter(":Name",model.Name),
                new DmParameter(":City",model.City)
            };
            return _client.ExecuteAdd(sql, paras);
        }
        public bool Update(PersonModel model)
            string sql = "update Person set City=:City where Id=:Id";
                new DmParameter(":Id",model.Id),
            return _client.ExecuteSql(sql, paras) > 0 ? true : false;
        public bool Delete(int id)
            string sql = "delete from Person where Id=:Id";
                new DmParameter(":Id",id),
        public PersonModel Get(int id)
            string sql = "select Id,Name,City from Person where Id=:Id";
            PersonModel model = null;
            using (var reader = (DmDataReader)_client.ExecuteReader(sql, paras))
            {
                while (reader.Read())
                {
                    model = new PersonModel();
                    model.Id = reader.GetInt32(0);
                    model.Name = reader.GetString(1);
                    model.City = reader.GetString(2);
                }
            }
            return model;
        public List<PersonModel> GetList()
            var list = new List<PersonModel>();
            using (var reader = (DmDataReader)_client.ExecuteReader("select Id,Name,City from Person"))
                    var model = new PersonModel();
                    list.Add(model);
            return list;
    }

需要注意达梦数据库的参数是用冒号作为前缀的。另外数据表和字段的名字建议全部使用大写字母，单词之间使用下划线分隔，也就是蛇形命名法。此时SQL语句就不用关心大小写了，怎么写都行。

Dapper方式

Dapper是一个轻量级的ORM框架，现在使用的也很广泛，可以简化代码编写。因为Dapper扩展的IDbConnection，这是ADO.NET中的东西，我们使用的DmProvider也是实现了ADO.NET相关接口，所以Dapper可以通过DmProvider操作达梦数据库。

首先定义一个获取数据库连接对象的工厂类：

 public class DmConnectionFactory
    {
        static string sqlConnString = "Server=127.0.0.1; UserId=TESTDB; PWD=123456";
        public static IDbConnection GetConn()
        {
            return new DmConnection(sqlConnString);
        }
    }

然后就可以使用它执行SQL语句了：

 public class PersonDapperDAL : IPersonDAL
    {
        public PersonDapperDAL()
        {
        }
        public PersonModel Get(int id)
        {
            string sql = "select Id,Name,City from Person where Id=:Id";
            return DmConnectionFactory.GetConn().QueryFirstOrDefault<PersonModel>(sql, new { Id = id });
        }
        public List<PersonModel> GetList()
        {
            string sql = "select Id,Name,City from Person";
            return DmConnectionFactory.GetConn().Query<PersonModel>(sql).ToList();
        }
        public int Add(PersonModel model)
        {
            string sql = "insert into Person(Name,City) Values(:Name,:City);Select @@IDENTITY";
            return DmConnectionFactory.GetConn().QuerySingle<int>(sql, model);
        }
        public bool Update(PersonModel model)
        {
            string sql = "update Person set City=:City where Id=:Id";
            int result = DmConnectionFactory.GetConn().Execute(sql, model);
            return result > 0;
        }
        public bool Delete(int id)
        {
            string sql = "delete from Person where Id=:Id";
            int result = DmConnectionFactory.GetConn().Execute(sql, new { Id = id });
            return result > 0;
        }
    }

Query、Execute这些方法都是Dapper定义的，可以看到能够少写很多代码。这里也不用打开连接、关闭连接，也不用写using，因为Dapper的这些方法中已经做了相关处理。

到此这篇关于国产化之 .NET Core 操作达梦数据库DM8的两种方式的文章就介绍到这了,更多相关.NET Core 达梦数据库DM8内容请搜索我们以前的文章或继续浏览下面的相关文章希望大家以后多多支持我们！