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.NET Core 达梦数据库DM8

波斯马 人气:0

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

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。

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