在 C# 中从 DBMS_OUTPUT.GET_LINES 获取输出缓冲区

Question

我试图通过 C# 从我的匿名 PL/SQL 块中的 DBMS_OUTPUT.PUT_LINE() 方法获取输出。我在这里查看了其他几个相关问题，但仍然遇到问题。 return执行匿名块的代码是returning -1，根据docs.

应该是正确的

我将 DBMS_OUTPUT.ENABLE() 设置为 NULL 以便不设置特定的缓冲区大小，然后使用 DBMS_OUTPUT.GET_LINES() 方法从该缓冲区获取行。

它 return 缓冲区中没有任何内容（空的 OracleString[]）和 return 0 行。我的匿名 PL/SQL 块很简单，但应该适用于任何。

DECLARE
    lvsName VARCHAR2(6) := 'Oracle';
BEGIN
    DBMS_OUTPUT.PUT_LINE('Do you see me?');
    DBMS_OUTPUT.PUT_LINE('My name is: ' || lvsName);    
END;

我错过了什么？

using (OracleDataAdapter oda = new OracleDataAdapter())
using (OracleCommand cmd = new OracleCommand(sql, _connection))
{
    // Execute anonymous PL/SQL block
    cmd.CommandType = CommandType.Text;
    var res = cmd.ExecuteNonQuery();

    // Set output Buffer
    cmd.CommandText = "BEGIN DBMS_OUTPUT.ENABLE(NULL); END;";
    cmd.CommandType = CommandType.Text;
    cmd.ExecuteNonQuery();

    // Get output
    cmd.CommandText = "BEGIN DBMS_OUTPUT.GET_LINES(:outString, :numLines); END;";
    cmd.CommandType = CommandType.Text;
    cmd.Parameters.Clear();
    cmd.Parameters.Add(new OracleParameter("outString", OracleDbType.Varchar2, int.MaxValue, ParameterDirection.Output));
    cmd.Parameters["outString"].CollectionType = OracleCollectionType.PLSQLAssociativeArray;
    cmd.Parameters["outString"].Size = sql.Length;
    cmd.Parameters["outString"].ArrayBindSize = new int[sql.Length];
    cmd.Parameters.Add(new OracleParameter("numLines", OracleDbType.Int32, ParameterDirection.InputOutput));
    cmd.Parameters["numLines"].Value = 10; // Get 10 lines
    cmd.ExecuteNonQuery();

     int numLines = Convert.ToInt32(cmd.Parameters["numLines"].Value.ToString());
     string outString = string.Empty;

     // Try to get more lines until there are zero left
     while (numLines > 0)
     {
         for (int i = 0; i < numLines; i++)
         {
             OracleString s = (OracleString)cmd.Parameters["outString"].Value;
             outString += s.ToString();
         }

         cmd.ExecuteNonQuery();
         numLines = Convert.ToInt32(cmd.Parameters["numLines"].Value.ToString());
     }

     return outString;
}

Answer 1

我不会说 C#，但我没有在您的代码中看到您在哪里为 numLines 变量赋值。

  DBMS_OUTPUT.GET_LINES (
   lines       OUT     CHARARR,
   numlines    IN OUT  INTEGER);

plsql 中的示例：

DECLARE
   v_array       DBMS_OUTPUT.CHARARR;
   v_lines   NUMBER;
BEGIN
   DBMS_OUTPUT.PUT_LINE ('aaaaa');
   DBMS_OUTPUT.put_line ('bbbb');
   DBMS_OUTPUT.put_line ('ccccc');
   v_lines := 1000; -- Number of lines you want to retrieve from the buffer.  
   DBMS_OUTPUT.GET_LINES (v_array, v_lines);

   DBMS_OUTPUT.put_line(v_lines); -- Lines retrieved from buffer.
   FOR idx IN nvl(v_array.FIRST,1) .. nvl(v_array.LAST,-1)
   LOOP
      DBMS_OUTPUT.put_line (v_array (idx));
   END LOOP;
END;

Answer 2

在我看来你的顺序有误...

// Execute anonymous PL/SQL block
cmd.CommandType = CommandType.Text;
var res = cmd.ExecuteNonQuery();

// Set output Buffer
cmd.CommandText = "BEGIN DBMS_OUTPUT.ENABLE(NULL); END;";
cmd.CommandType = CommandType.Text;
cmd.ExecuteNonQuery();

// Get output
cmd.CommandText = "BEGIN DBMS_OUTPUT.GET_LINES(:outString, :numLines); END;";

在设置（启用）DBMS_OUTPUT 和使用 GET_LINES 获取输出之间应该是您的写入命令，但它是您执行的第一件事。

尝试更改顺序。让我知道它是否有效，因为我没有尝试过（我不习惯 C#...我在 Java 中有它）。

Answer 3

您的代码的主要问题是它没有为输出缓冲区的每个元素设置绑定大小。检索结果时也没有正确索引输出缓冲区。最后，执行顺序也很重要：在执行匿名代码块之前，您必须首先启用输出。所做的每一项更改都会在下面 MCVE 中进行评论。仅进行必要的更改以使其正常工作。

static void Main(string[] args)
{
    string str = "User Id=xxx; password=xxx; Data Source=localhost:1521/xxx;";
    string sql = @"DECLARE lvsName VARCHAR2(6) := 'Oracle'; BEGIN  DBMS_OUTPUT.PUT_LINE('Do you see me?'); DBMS_OUTPUT.PUT_LINE('My name is: ' || lvsName); END;";

    OracleConnection _connection = new OracleConnection(str);

    try
    {
        _connection.Open();

        //adapter not being used
        //using (OracleDataAdapter oda = new OracleDataAdapter())

        using (OracleCommand cmd = new OracleCommand(sql, _connection))
        {
            // First enable buffer output
            // Set output Buffer
            cmd.CommandText = "BEGIN DBMS_OUTPUT.ENABLE(NULL); END;";
            cmd.CommandType = CommandType.Text;
            cmd.ExecuteNonQuery();

            // Then execute anonymous block
            // Execute anonymous PL/SQL block
            cmd.CommandText = sql;
            cmd.CommandType = CommandType.Text;
            var res = cmd.ExecuteNonQuery();


            // Get output
            cmd.CommandText = "BEGIN DBMS_OUTPUT.GET_LINES(:outString, :numLines); END;";
            cmd.CommandType = CommandType.Text;

            cmd.Parameters.Clear();

            cmd.Parameters.Add(new OracleParameter("outString", OracleDbType.Varchar2, int.MaxValue, ParameterDirection.Output));
            cmd.Parameters["outString"].CollectionType = OracleCollectionType.PLSQLAssociativeArray;
            cmd.Parameters["outString"].Size = sql.Length;
            cmd.Parameters["outString"].ArrayBindSize = new int[sql.Length];

            // set bind size for each array element
            for (int i = 0; i < sql.Length; i++)
            {
                cmd.Parameters["outString"].ArrayBindSize[i] = 32000;
            }


            cmd.Parameters.Add(new OracleParameter("numLines", OracleDbType.Int32, ParameterDirection.InputOutput));
            cmd.Parameters["numLines"].Value = 10; // Get 10 lines
            cmd.ExecuteNonQuery();

            int numLines = Convert.ToInt32(cmd.Parameters["numLines"].Value.ToString());
            string outString = string.Empty;

            // Try to get more lines until there are zero left
            while (numLines > 0)
            {
                for (int i = 0; i < numLines; i++)
                {
                    // use proper indexing here
                    //OracleString s = (OracleString)cmd.Parameters["outString"].Value;
                    OracleString s = ((OracleString[])cmd.Parameters["outString"].Value)[i];
                    outString += s.ToString();

                    // add new line just for formatting
                    outString += "\r\n";
                }

                cmd.ExecuteNonQuery();
                numLines = Convert.ToInt32(cmd.Parameters["numLines"].Value.ToString());
            }

            Console.WriteLine(outString);
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.ToString());
    }

    _connection.Close();
    _connection.Dispose();

    Console.WriteLine("Press RETURN to exit.");
    Console.ReadLine();
}

输出结果为：

Do you see me?
My name is: Oracle

Press RETURN to exit.

Answer 4

感谢 jsanalytics 的上述回答，它为解决方案提供了良好的基础。不过，上述解决方案存在一些问题，主要与 sql.Length 在许多没有意义的地方的使用有关。这是一个可重用的解决方案，它纠正了一些问题。

using Oracle.DataAccess.Client;
using Oracle.DataAccess.Types;
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;

namespace MyNamespace
{
    public static class DbmsOutputHelper
    {
        public const int DefaultReadBatchSize = 10;

        public static void EnableDbmsOutput(this OracleConnection conn)
        {
            using (var cmd = conn.CreateCommand())
            {
                cmd.CommandText = "DBMS_OUTPUT.ENABLE";
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.ExecuteNonQuery();
            }
        }

        public static void DisableDbmsOutput(this OracleConnection conn)
        {
            using (var cmd = conn.CreateCommand())
            {
                cmd.CommandText = "DBMS_OUTPUT.DISABLE";
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.ExecuteNonQuery();
            }
        }

        public static List<string> ReadDbmsOutput(this OracleConnection conn, int readBatchSize = DefaultReadBatchSize)
        {
            if (readBatchSize <= 0)
            {
                throw new ArgumentOutOfRangeException(nameof(readBatchSize), "must be greater than zero");
            }

            using (var cmd = conn.CreateCommand())
            {
                cmd.CommandText = "DBMS_OUTPUT.GET_LINES";
                cmd.CommandType = CommandType.StoredProcedure;

                var linesParam = cmd.Parameters.Add(new OracleParameter("lines", OracleDbType.Varchar2, int.MaxValue, ParameterDirection.Output));
                linesParam.CollectionType = OracleCollectionType.PLSQLAssociativeArray;
                linesParam.Size = readBatchSize;
                linesParam.ArrayBindSize = Enumerable.Repeat(32767, readBatchSize).ToArray();   // set bind size for each array element

                var numLinesParam = cmd.Parameters.Add(new OracleParameter("numlines", OracleDbType.Int32, ParameterDirection.InputOutput));

                var result = new List<string>();
                int numLinesRead;

                do
                {
                    numLinesParam.Value = readBatchSize;
                    cmd.ExecuteNonQuery();
                    numLinesRead = ((OracleDecimal)numLinesParam.Value).ToInt32();

                    var values = (OracleString[])linesParam.Value;

                    for (int i = 0; i < numLinesRead; i++)
                    {
                        result.Add(values[i].ToString());
                    }

                } while (numLinesRead == readBatchSize);

                return result;
            }
        }
    }
}

在 C# 中从 DBMS_OUTPUT.GET_LINES 获取输出缓冲区

Getting output buffer from DBMS_OUTPUT.GET_LINES in C#

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