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：www.dameng.com/list_103.ht…
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 /// <summary> /// 执行一条SQL语句，确定记录是否存在 /// </summary> /// <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; } /// <summary> /// 执行一条SQL语句，确定记录是否存在 /// </summary> /// <param name="sql">SQL查询语句</param> /// <returns></returns> public async Task<bool> ExistsAsync(string sql) { object obj = await GetSingleAsync(sql); int cmdresult; if (Equals(obj, null) || Equals(obj, DBNull.Value)) { cmdresult = 0; } else { cmdresult = int.Parse(obj.ToString()); } return cmdresult > 0; } /// <summary> /// 执行一条SQL语句，确定记录是否存在 /// </summary> /// <param name="sql">SQL查询语句</param> /// <param name="paras">SQL参数数组</param> /// <returns></returns> public bool Exists(string sql, params DmParameter[] paras) { object obj = GetSingle(sql, paras); int cmdresult; if ((object.Equals(obj, null)) || (object.Equals(obj, DBNull.Value))) { cmdresult = 0; } else { cmdresult = int.Parse(obj.ToString()); } return cmdresult > 0; } /// <summary> /// 执行一条SQL语句，确定记录是否存在 /// </summary> /// <param name="sql">SQL查询语句</param> /// <param name="paras">SQL参数数组</param> /// <returns></returns> public async Task<bool> ExistsAsync(string sql, params DmParameter[] paras) { object obj = await GetSingleAsync(sql, paras); int cmdresult; if ((object.Equals(obj, null)) || (object.Equals(obj, DBNull.Value))) { cmdresult = 0; } else { cmdresult = int.Parse(obj.ToString()); } return cmdresult > 0; } /// <summary> /// 获取记录条数 /// </summary> /// <param name="tableName">表名</param> /// <param name="sqlCondition">查询条件</param> /// <returns></returns> 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); } else { return 0; } } /// <summary> /// 获取记录条数 /// </summary> /// <param name="tableName">表名</param> /// <param name="sqlCondition">查询条件</param> /// <returns></returns> public async Task<int> GetCountAsync(string tableName, string sqlCondition) { string sql = "select count(1) from `" + tableName + "`"; if (!string.IsNullOrWhiteSpace(sqlCondition)) { sql += " where " + sqlCondition; } object result = await GetSingleAsync(sql); if (result != null) { return Convert.ToInt32(result); } else { return 0; } } /// <summary> /// 获取记录条数 /// </summary> /// <param name="tableName">表名</param> /// <param name="sqlCondition">查询条件</param> /// <param name="paras">SQL参数数组</param> /// <returns></returns> public int GetCount(string tableName, string sqlCondition, DmParameter[] paras) { string sql = "select count(1) from `" + tableName + "`"; if (!string.IsNullOrWhiteSpace(sqlCondition)) { sql += " where " + sqlCondition; } object result = GetSingle(sql, paras); if (result != null) { return Convert.ToInt32(result); } else { return 0; } } /// <summary> /// 获取记录条数 /// </summary> /// <param name="tableName">表名</param> /// <param name="sqlCondition">查询条件</param> /// <param name="paras">SQL参数数组</param> /// <returns></returns> public async Task<int> GetCountAsync(string tableName, string sqlCondition, DmParameter[] paras) { string sql = "select count(1) from `" + tableName + "`"; if (!string.IsNullOrWhiteSpace(sqlCondition)) { sql += " where " + sqlCondition; } object result = await GetSingleAsync(sql, paras); if (result != null) { return Convert.ToInt32(result); } else { return 0; } } #endregion 通用快捷方法 #region 执行简单SQL语句 /// <summary> /// 执行SQL语句，返回影响的记录数 /// </summary> /// <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; } } } /// <summary> /// 执行SQL语句，返回影响的记录数 /// </summary> /// <param name="sql">SQL语句</param> /// <returns>影响的记录数</returns> public async Task<int> ExecuteSqlAsync(string sql) { using (DmConnection connection = new DmConnection(connectionString)) { using (DmCommand cmd = new DmCommand(sql, connection)) { await connection.OpenAsync(); int rows = await cmd.ExecuteNonQueryAsync(); return rows; } } } /// <summary> /// 执行SQL语句，返回影响的记录数（可自定义超时时间） /// </summary> /// <param name="sql">SQL语句</param> /// <param name="timeout">执行超时时间</param> /// <returns>影响的记录数</returns> public int ExecuteSqlByTime(string sql, int timeout) { using (DmConnection connection = new DmConnection(this.connectionString)) { using (DmCommand cmd = new DmCommand(sql, connection)) { connection.Open(); cmd.CommandTimeout = timeout; int rows = cmd.ExecuteNonQuery(); return rows; } } } /// <summary> /// 执行SQL语句，返回影响的记录数（可自定义超时时间） /// </summary> /// <param name="sql">SQL语句</param> /// <param name="timeout">执行超时时间</param> /// <returns>影响的记录数</returns> public async Task<int> ExecuteSqlByTimeAsync(string sql, int timeout) { using (DmConnection connection = new DmConnection(this.connectionString)) { using (DmCommand cmd = new DmCommand(sql, connection)) { await connection.OpenAsync(); cmd.CommandTimeout = timeout; int rows = await cmd.ExecuteNonQueryAsync(); return rows; } } } /// <summary> /// 执行多条SQL语句，实现数据库事务。 /// </summary> /// <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; } } } } } /// <summary> /// 执行多条SQL语句，实现数据库事务。 /// </summary> /// <param name="sqlList">多条SQL语句</param> public async Task ExecuteSqlTransAsync(ArrayList sqlList) { using (DmConnection conn = new DmConnection(connectionString)) { await conn.OpenAsync(); using (DbTransaction trans = await conn.BeginTransactionAsync()) { 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; await cmd.ExecuteNonQueryAsync(); } } trans.Commit(); } catch (DmException ex) { trans.Rollback(); throw ex; } } } } } /// <summary> /// 执行一条SQL查询语句，返回查询结果。 /// </summary> /// <param name="sql">SQL查询语句</param> /// <returns>查询结果</returns> public object GetSingle(string sql) { using (DmConnection connection = new DmConnection(connectionString)) { using (DmCommand cmd = new DmCommand(sql, connection)) { connection.Open(); object obj = cmd.ExecuteScalar(); if ((object.Equals(obj, null)) || (object.Equals(obj, DBNull.Value))) { return null; } else { return obj; } } } } /// <summary> /// 执行一条SQL查询语句，返回查询结果。 /// </summary> /// <param name="sql">SQL查询语句</param> /// <returns>查询结果</returns> public async Task<object> GetSingleAsync(string sql) { using (DmConnection connection = new DmConnection(connectionString)) { using (DmCommand cmd = new DmCommand(sql, connection)) { await connection.OpenAsync(); object obj = await cmd.ExecuteScalarAsync(); if ((object.Equals(obj, null)) || (object.Equals(obj, DBNull.Value))) { return null; } else { return obj; } } } } /// <summary> /// 执行查询语句，返回DbDataReader（切记要手工关闭DbDataReader） /// </summary> /// <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(); } /// <summary> /// 执行查询语句，返回DbDataReader（切记要手工关闭DbDataReader） /// </summary> /// <param name="sql">查询语句</param> /// <returns>DmDataReader</returns> public async Task<DbDataReader> ExecuteReaderAsync(string sql) { DmConnection connection = new DmConnection(connectionString); DmCommand cmd = new DmCommand(sql, connection); await connection.OpenAsync(); return await cmd.ExecuteReaderAsync(); } /// <summary> /// 执行查询语句，返回DataSet /// </summary> /// <param name="sql">查询语句</param> /// <returns>DataSet</returns> public DataSet Query(string sql) { using (DmConnection connection = new DmConnection(connectionString)) { using (DmDataAdapter command = new DmDataAdapter(sql, connection)) { DataSet ds = new DataSet(); connection.Open(); command.Fill(ds, "ds"); return ds; } } } /// <summary> /// 执行查询语句，返回DataSet（可自定义超时时间） /// </summary> /// <param name="sql"></param> /// <param name="timeout"></param> /// <returns></returns> public DataSet Query(string sql, int timeout) { using (DmConnection connection = new DmConnection(connectionString)) { using (DmDataAdapter command = new DmDataAdapter(sql, connection)) { DataSet ds = new DataSet(); connection.Open(); command.SelectCommand.CommandTimeout = timeout; command.Fill(ds, "ds"); return ds; } } } #endregion 执行简单SQL语句 #region 执行带参数的SQL语句 /// <summary> /// 执行SQL语句，返回影响的记录数 /// </summary> /// <param name="sql">SQL语句</param> /// <param name="paras">SQL参数数组</param> /// <returns>影响的记录数</returns> public int ExecuteSql(string sql, params DmParameter[] paras) { using (DmConnection connection = new DmConnection(connectionString)) { using (DmCommand cmd = new DmCommand()) { PrepareCommand(cmd, connection, null, sql, paras); int rows = cmd.ExecuteNonQuery(); cmd.Parameters.Clear(); return rows; } } } /// <summary> /// 执行SQL语句，返回影响的记录数 /// </summary> /// <param name="sql">SQL语句</param> /// <param name="paras">SQL参数数组</param> /// <returns>影响的记录数</returns> public async Task<int> ExecuteSqlAsync(string sql, params DmParameter[] paras) { using (DmConnection connection = new DmConnection(connectionString)) { using (DmCommand cmd = new DmCommand()) { await PrepareCommandAsync(cmd, connection, null, sql, paras); int rows = await cmd.ExecuteNonQueryAsync(); cmd.Parameters.Clear(); return rows; } } } /// <summary> /// 执行添加SQL语句，返回记录的ID（自动产生的自增主键） /// </summary> /// <param name="sql">SQL语句</param> /// <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"; using (DmConnection connection = new DmConnection(connectionString)) { using (DmCommand cmd = new DmCommand()) { PrepareCommand(cmd, connection, null, sql, parms); int recordID = Int32.Parse(cmd.ExecuteScalar().ToString()); cmd.Parameters.Clear(); return recordID; } } } /// <summary> /// 执行添加SQL语句，返回记录的ID（自动产生的自增主键） /// </summary> /// <param name="sql">SQL语句</param> /// <param name="parms">SQL参数</param> /// <returns>记录的ID</returns> public async Task<int> ExecuteAddAsync(string sql, params DmParameter[] parms) { sql = sql + ";select @@identity as newautoid"; using (DmConnection connection = new DmConnection(connectionString)) { using (DmCommand cmd = new DmCommand()) { await PrepareCommandAsync(cmd, connection, null, sql, parms); int recordID; try { recordID = int.Parse((await cmd.ExecuteScalarAsync()).ToString()); } catch { recordID = -1; } cmd.Parameters.Clear(); return recordID; } } } /// <summary> /// 执行多条SQL语句，实现数据库事务。 /// </summary> /// <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) { using (DmConnection conn = new DmConnection(connectionString)) { conn.Open(); using (DbTransaction trans = conn.BeginTransaction()) { using (DmCommand cmd = new DmCommand()) { try { 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(); } trans.Commit(); } catch (DmException ex) { trans.Rollback(); throw ex; } } } } } /// <summary> /// 执行多条SQL语句，实现数据库事务。 /// </summary> /// <param name="sqlList">SQL语句的哈希表（key为sql语句，value是该语句的DmParameter[]）</param> public async Task ExecuteSqlTransAsync(Hashtable sqlList) { using (DmConnection conn = new DmConnection(connectionString)) { await conn.OpenAsync(); using (DbTransaction trans = conn.BeginTransaction()) { using (DmCommand cmd = new DmCommand()) { try { foreach (DictionaryEntry entry in sqlList) { var sql = entry.Key.ToString(); var paras = (DmParameter[])entry.Value; await PrepareCommandAsync(cmd, conn, trans, sql, paras); int val = await cmd.ExecuteNonQueryAsync(); cmd.Parameters.Clear(); } trans.Commit(); } catch (DmException ex) { trans.Rollback(); throw ex; } } } } } /// <summary> /// 执行一条计算查询结果语句，返回查询结果。 /// </summary> /// <param name="sql">SQL语句</param> /// <param name="parms">SQL参数</param> /// <returns>查询结果</returns> public object GetSingle(string sql, params DmParameter[] parms) { using (DmConnection conn = new DmConnection(connectionString)) { using (DmCommand cmd = new DmCommand()) { PrepareCommand(cmd, conn, null, sql, parms); object obj = cmd.ExecuteScalar(); cmd.Parameters.Clear(); if ((object.Equals(obj, null)) || (object.Equals(obj, DBNull.Value))) { return null; } else { return obj; } } } } /// <summary> /// 执行一条计算查询结果语句，返回查询结果。 /// </summary> /// <param name="sql">SQL语句</param> /// <param name="parms">SQL参数</param> /// <returns>查询结果</returns> public async Task<object> GetSingleAsync(string sql, params DmParameter[] parms) { using (DmConnection conn = new DmConnection(connectionString)) { using (DmCommand cmd = new DmCommand()) { await PrepareCommandAsync(cmd, conn, null, sql, parms); object obj = await cmd.ExecuteScalarAsync(); cmd.Parameters.Clear(); if ((object.Equals(obj, null)) || (object.Equals(obj, DBNull.Value))) { return null; } else { return obj; } } } } /// <summary> /// 执行查询语句，返回DmDataReader (切记要手工关闭DmDataReader) /// </summary> /// <param name="sql">查询语句</param> /// <param name="parms">SQL参数</param> /// <returns>DmDataReader</returns> public DbDataReader ExecuteReader(string sql, params DmParameter[] parms) { DmConnection connection = new DmConnection(connectionString); DmCommand cmd = new DmCommand(); PrepareCommand(cmd, connection, null, sql, parms); DbDataReader myReader = cmd.ExecuteReader(); cmd.Parameters.Clear(); return myReader; } /// <summary> /// 执行查询语句，返回DmDataReader (切记要手工关闭DmDataReader) /// </summary> /// <param name="sql">查询语句</param> /// <param name="parms">SQL参数</param> /// <returns>DmDataReader</returns> public async Task<DbDataReader> ExecuteReaderAsync(string sql, params DmParameter[] parms) { DmConnection connection = new DmConnection(connectionString); DmCommand cmd = new DmCommand(); await PrepareCommandAsync(cmd, connection, null, sql, parms); var myReader = await cmd.ExecuteReaderAsync(); cmd.Parameters.Clear(); return myReader; } /// <summary> /// 执行查询语句，返回DataSet /// </summary> /// <param name="sql">查询语句</param> /// <param name="paras">参数数组</param> /// <returns>DataSet</returns> public DataSet Query(string sql, params DmParameter[] paras) { using (DmConnection connection = new DmConnection(connectionString)) { using (DmCommand cmd = new DmCommand()) { PrepareCommand(cmd, connection, null, sql, paras); DataSet ds = new DataSet(); using (DmDataAdapter da = new DmDataAdapter(cmd)) { da.Fill(ds, "ds"); cmd.Parameters.Clear(); return ds; } } } } /// <summary> /// 准备SQL查询命令 /// </summary> /// <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> /// <param name="paras">SQL参数数组</param> private void PrepareCommand(DmCommand cmd, DmConnection conn, DbTransaction trans, string cmdText, DmParameter[] paras) { if (conn.State != ConnectionState.Open) { conn.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); } } } /// <summary> /// 准备SQL查询命令 /// </summary> /// <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> /// <param name="paras">SQL参数数组</param> private async Task PrepareCommandAsync(DmCommand cmd, DmConnection conn, DbTransaction trans, string cmdText, DmParameter[] paras) { if (conn.State != ConnectionState.Open) { await conn.OpenAsync(); } 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); } } } #endregion 执行带参数的SQL语句 }
