相关代码    /// <summary>
    /// 返回CLOB数据类型的字符串形式
    /// </summary>
    /// <param name="sql">查询sql语句</param>
    /// <returns>查询到的值</returns>
    public string GetSealString(string sql)
    {
        OracleCommand oraCmd = new OracleCommand();
        string ContentBySeal = string.Empty;
        try
        {
            OraOpen();
            oraCmd.Connection = ORAConn;
            oraCmd.CommandText = sql;            OracleDataReader reader = oraCmd.ExecuteReader();            if (reader.Read())
            {
                OracleLob myLob = reader.GetOracleLob(0);
                StreamReader Sreader = new StreamReader(myLob, Encoding.Unicode);                int actual = 0;
                char[] content = new char[6000];
                while ((actual = Sreader.Read(content, 0, content.Length)) > 0)
                {
                    ContentBySeal = new string(content, 0, actual);
                }
            }
        }
        catch (OracleException oex)
        {
            throw new ApplicationException(oex.Message);
        }
        finally
        {
            OraClose();
        }
        return ContentBySeal;
    }    /// <summary>
    /// 获取CLOB字符类型的字符串格式
    /// </summary>
    /// <returns></returns>
    private string GetVise(string BILLNUM,string index)
    {
        string getCmd = "Select DOCSIGNPIC from ELECSEAL where APPTYPE='MATRECBILL' and SEALGRP like '_"+index+"%' and BILLNUM='" + BILLNUM + "' order by SEALGRP asc;";
        string seal = OracleDB.GetSealString(getCmd);
        return seal;
    }