国产化中的|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。
国产化中的|国产化中的 .NET Core 操作达梦数据库DM8的两种方式(操作详解)
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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。
国产化中的|国产化中的 .NET Core 操作达梦数据库DM8的两种方式(操作详解)
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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; /// /// 初始化DMClient的一个新实例/// /// 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/// SQL查询语句/// public bool Exists(string sql)object obj = GetSingle(sql); int cmdresult; if (Equals(obj, null) || Equals(obj, DBNull.Value)){cmdresult = 0; }elsecmdresult = int.Parse(obj.ToString()); return cmdresult > 0; public async Task ExistsAsync(string sql)object obj = await GetSingleAsync(sql); /// SQL参数数组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 ExistsAsync(string sql, params DmParameter[] paras)object obj = await GetSingleAsync(sql, paras); /// 获取记录条数/// 表名/// 查询条件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 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 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/// SQL语句/// 影响的记录数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 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)/// 执行超时时间public int ExecuteSqlByTime(string sql, int timeout)using (DmConnection connection = new DmConnection(this.connectionString))cmd.CommandTimeout = timeout; public async Task ExecuteSqlByTimeAsync(string sql, int timeout)/// 执行多条SQL语句,实现数据库事务。/// 多条SQL语句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。/// 查询结果public object GetSingle(string sql)object obj = cmd.ExecuteScalar(); if ((object.Equals(obj, null)) || (object.Equals(obj, DBNull.Value)))return null; elsereturn obj; public async Task 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)/// 查询语句/// DmDataReaderpublic DbDataReader ExecuteReader(string sql)DmConnection connection = new DmConnection(connectionString); DmCommand cmd = new DmCommand(sql, connection); connection.Open(); return cmd.ExecuteReader(); public async Task ExecuteReaderAsync(string sql)await connection.OpenAsync(); return await cmd.ExecuteReaderAsync(); /// 执行查询语句,返回DataSet/// DataSetpublic 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)/// /// 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 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)/// SQL参数/// 记录的IDpublic 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 ExecuteAddAsync(string sql, params DmParameter[] parms)sql = sql + "; select @@identity as newautoid"; await PrepareCommandAsync(cmd, connection, null, sql, parms); int recordID; tryrecordID = int.Parse((await cmd.ExecuteScalarAsync()).ToString()); catchrecordID = -1; /// SQL语句的哈希表(key为sql语句,value是该语句的DmParameter[])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 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 ExecuteReaderAsync(string sql, params DmParameter[] parms)await PrepareCommandAsync(cmd, connection, null, sql, parms); var myReader = await cmd.ExecuteReaderAsync(); /// 参数数组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/// SQL命令对象/// SQL连接对象/// SQL事务对象/// SQL语句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 =https://www.it610.com/article/= 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 GetList()var list = new List(); 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(sql, new { Id = id }); }public List GetList(){string sql = "select Id,Name,City from Person"; return DmConnectionFactory.GetConn().Query(sql).ToList(); }public int Add(PersonModel model){string sql = "insert into Person(Name,City) Values(:Name,:City); Select @@IDENTITY"; return DmConnectionFactory.GetConn().QuerySingle(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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