C#访问Oracle数据库

随着时间的推移知识也在更新，原来可用的技术也会被淘汰或更新。

framework4.0开始不再支持System.Data.OracleClient了，但是令人欣慰的是ORACLE公司自己出了一个Oracle.ManagedDataAccess链接库。

下载地址：https://files.cnblogs.com/files/weipt/OracleBase.rar

添加引用之后就可以在c#中使用了。

1.连接字符串如下

<connectionStrings>
<add name="ConnectionString" connectionString="server=server;uid=sa;pwd=sa;database=dy_db;"/>
<add name="ConnectionString_Oralce" connectionString="Data Source=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.3.254)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=tdc)));Persist Security Info=True;User ID=tdc;Password=tdc;"/>
</connectionStrings>

不用建立tns监听文件，不用安装庞大的oracle数据库客户端

2.建立公共的数据访问方法

    /// <summary>
        /// 执行SQL语句，返回影响的记录数
        /// </summary>
        /// <param name="SQLString">SQL语句</param>
        /// <returns>影响的记录数</returns>
        public static int ExecuteSql(string SQLString)
        {
            using (OracleConnection connection = new OracleConnection(connectionString))
            {                
                using (OracleCommand cmd = new OracleCommand(SQLString,connection))
                {
                    try
                    {        
                        connection.Open();
                        int rows=cmd.ExecuteNonQuery();
                        return rows;
                    }
                    catch(OracleException E)
                    {                    
                        connection.Close();
                        throw new Exception(E.Message);
                    }
                }                
            }
        }

        /// <summary>
        /// 执行SQL语句，返回影响的记录数
        /// </summary>
        /// <param name="SQLString">SQL语句</param>
        /// <returns>影响的记录数</returns>
        public static int ExecuteSql(string SQLString,params OracleParameter[] cmdParms)
        {
            using (OracleConnection connection = new OracleConnection(connectionString))
            {                
                using (OracleCommand cmd = new OracleCommand())
                {
                    try
                    {        
                        PrepareCommand(cmd, connection, null,SQLString, cmdParms);
                        int rows=cmd.ExecuteNonQuery();
                        cmd.Parameters.Clear();
                        return rows;
                    }
                    catch(OracleException E)
                    {                
                        throw new Exception(E.Message);
                    }
                }                
            }
        }

    /// <summary>
        /// 执行查询语句，返回DataSet
        /// </summary>
        /// <param name="SQLString">查询语句</param>
        /// <returns>DataSet</returns>
        public static DataSet Query(string SQLString)
        {
            using (OracleConnection connection = new OracleConnection(connectionString))
            {
                DataSet ds = new DataSet();
                try
                {
                    connection.Open();
                    OracleDataAdapter command = new OracleDataAdapter(SQLString,connection);                
                    command.Fill(ds,"ds");
                }
                catch(OracleException ex)
                {                
                    throw new Exception(ex.Message);
                }            
                return ds;
            }            
        }

3.使用时和sqlserver不同的地方

1>如果采用sql字符串查询，那么查询语句要遵循ORACLE标准，日期格式要用

to_date('2017-05-24 12:12:12','yyyy-mm-dd hh24:mi:ss')

2>不支持top关键字等关键字

3>如果用传参执行的化，不用转换日期格式，但是不是@了，而是：冒号

    /// <summary>
        /// 更新一条数据
        /// </summary>
        public bool Update(OMaticsoft.Model.MDEVICECRUNTIME model)
        {
            StringBuilder strSql=new StringBuilder();
            strSql.Append("update DEVICECRUNTIME set ");
            strSql.Append("PARAVALUE=:PARAVALUE,");
            strSql.Append("RECEIVETIME=:RECEIVETIME");
            strSql.Append(" where DEVICEID=:DEVICEID and RESNAME=:RESNAME");
            OracleParameter[] parameters = {
                    new OracleParameter("PARAVALUE", OracleDbType.NVarchar2,50),
                    new OracleParameter("RECEIVETIME", OracleDbType.Date),
                    new OracleParameter("DEVICEID", OracleDbType.Int32,4),
                    //new OracleParameter("RUMTIMEID", OracleDbType.Long,4),
                    new OracleParameter("RESNAME", OracleDbType.NVarchar2,50)};
            parameters[0].Value = model.PARAVALUE;
            parameters[1].Value = model.RECEIVETIME;
            parameters[2].Value = model.DEVICEID;
            //parameters[3].Value = model.RUMTIMEID;
            parameters[3].Value = model.RESNAME;

            int rows=DbHelperOra.ExecuteSql(strSql.ToString(),parameters);
            if (rows > 0)
            {
                return true;
            }
            else
            {
                return false;
            }
        }