c# - Oracle 日期格式 — 数据读取器无法识别 to_char 函数

Question

基本上只是在 YYYYMMDD 中提取日期，我可以在查询分析器中很好地完成此操作，但是当我尝试在 C# 中运行此查询时，我不断收到未找到列的错误，似乎也很难进行串联(但这并不是什么大问题)所以有点不确定这里发生了什么..我真的只是希望我的 to_char 函数能够工作。有想法吗？谢谢!

  string oradb = "user id=x;password=x;data source=(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)"
        +"(HOST=x)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=x)));";

    OracleConnection conn = new OracleConnection(oradb);
    conn.Open();

    OracleCommand cmd = new OracleCommand();
    cmd.Connection = conn;
    cmd.CommandType = CommandType.Text; 
    cmd.CommandText =
        "SELECT to_char(ProblemDate, 'yyyymmdd'), data1, data2,"
        +"data4, data5, data6"
        +" WHERE ( ProblemDate >='03-oct-2011' ) "
        +"AND ( ProblemDate <= '08-oct-2011' ) AND " 
        +"( data1 in ( '3','5','6' ) )";
    OracleDataReader dr = cmd.ExecuteReader();

    string fileOut1 = Request.PhysicalApplicationPath;
    string fileOut = fileOut1 + "Text5.txt";
    // Creates the file
    StreamWriter sw = new StreamWriter(fileOut);
    if (dr.HasRows)
    {
        while (dr.Read())
        {
            string data1= (string)dr["data1"].ToString();
            string data2 = (string)dr["data3"].ToString();
            string data3 = (string)dr["data4"];
            string data4 = (string)dr["data5"].ToString();
            string data5 = (string)dr["data6"].ToString();
            string ProblemDate = (string)dr["ProblemDate"].ToString();

            //remove the comma
            char[] MyChar = { ',' };

            sw.WriteLine(data1.PadRight(10) + data2.PadRight(5) + data3.TrimEnd(MyChar) + "000" +
                data4 + "000" + data5+  ProblemDate + "  " + "N" );

            Label1.Text = "File created successfully.<br />";
            Label1.Text += fileOut1;
        }
        // Closes the connenction.
        sw.Close();
        conn.Close();
    }
    else
    {
        Label1.Text = "No data written.";
    }

Answer 1

首先，您可以从 Java 内部打印查询并查看实际触发的查询吗？

这些是我看到的问题......

SELECT to_char(ProblemDate, 'yyyymmdd'), data1, data2,
       data4, data5, data6
       WHERE ( ProblemDate >='03-oct-2011' )
         AND ( ProblemDate <= '08-oct-2011' ) 
         AND data1 in ( '3','5','6' ) );

1. 查询中没有 from 子句和 table_name。

2. 这可能不是问题的原因，但想指出来。由于您正在执行 to_char，我假设 ProblemDate 是日期数据类型。始终建议在比较时使用显式强制转换，因此将条件更改为

   ProblemDate >=to_date('03-oct-2011','dd-mon-yyyy') 和ProblemDate <=to_date('08-oct-2011',,'dd-mon-yyyy')