c# SqlCommandのデバッグ用テキストファイルを出力する ref: http://qiita.com/Implem/items/ce4f03c60f9011d0e37f

CommandTextForDebugging.sql

use [dbname];
declare @p1 nvarchar(4);                          set @p1 = 'hoge';

select [abc].[a], [abc].[b], [abc].[c],
 [abc].[d], [abc].[e] 
from [abc] 
where @p1

Debugs.cs

using System.Collections.Generic;
using System.Data.SqlClient;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
namespace Implem.Sample
{
    public static class Debugs
    {
        [Conditional("DEBUG")]
        public static void WriteCommandTextForDebugging(string dbName, SqlCommand sqlCommand)
        {
            // SqlCommandデバッグ用テキスト作成
            var commandTextForDebugging = new StringBuilder();
            commandTextForDebugging.Append("use [", dbName, "];\r\n");
            commandTextForDebugging.Append(GetDeclareParametersText(sqlCommand));
            commandTextForDebugging.Append(GetFormattedCommandText(sqlCommand));

            // テキストファイルに書き込み
            WriteFile(commandTextForDebugging.ToString(), @"c:\temp\CommandTextForDebugging.sql");
        }

        private static string GetFormattedCommandText(SqlCommand sqlCommand)
        {
            var commandTextFormatted = new StringBuilder();
            var commandTextTemp = sqlCommand.CommandText;

            // 特定の命令の前に改行を入れて読みやすくする
            commandTextTemp.RegexMatches(
                GetDelimitersForNewLine().Select(o => @"(?<!\n)\b" + o + @"\b").Join("|"),
                RegexOptions.Multiline)
                    .Cast<Match>()
                    .Select(o => o.Value)
                    .Distinct()
                    .ForEach(match =>
                        commandTextTemp = commandTextTemp.Replace(match, "\r\n" + match));

            // 1行あたりのカンマ区切りが3つを超えたら改行を入れて読みやすくする
            commandTextTemp.SplitReturn().ForEach(line =>
                commandTextFormatted.Append(line.Split(',')
                    .Chunk(3)
                    .Select(o => string.Join(",", o))
                    .Join(",\r\n") + "\r\n"));
            return commandTextFormatted.ToString();
        }

        private static string GetDeclareParametersText(SqlCommand sqlCommand)
        {
            var commandParameters = new StringBuilder();

            // パラメータ宣言を作成する
            foreach (SqlParameter parameter in sqlCommand.Parameters)
            {
                commandParameters.Append(
                    "{0, -50}".Params(GetDeclareParameterText(parameter)),
                    "set @", parameter.ParameterName,
                    " = '",
                    parameter.Value.ToString(),
                    "';\r\n");
            }
            return commandParameters.ToString();
        }

        private static string GetDeclareParameterText(SqlParameter parameter)
        {
            if (parameter.Size == 0)
            {
                return "declare @{0} {1}; ".Params(
                    parameter.ParameterName,
                    parameter.SqlDbType.ToString().ToLower());
            }
            else
            {
                return "declare @{0} {1}({2}); ".Params(
                    parameter.ParameterName,
                    parameter.SqlDbType.ToString().ToLower(),
                    parameter.Size);
            }
        }

        private static string[] GetDelimitersForNewLine()
        {
            // ここに列挙したキーワードの手前で改行（好みで追加/削除）
            return new string[]
            {
                "begin", "commit", "select", "insert into", "values", "update", "delete",
                "from", "inner join", "left outer join", "where","order by"
            };
        }

        private static IEnumerable<IEnumerable<T>> Chunk<T>(
            this IEnumerable<T> ienumerable, int size)
        {
            while (ienumerable.Any())
            {
                yield return ienumerable.Take(size);
                ienumerable = ienumerable.Skip(size);
            }
        }

        public static void WriteFile(string str, string path, string encoding = "utf-8")
        {
            using (var writer = new StreamWriter(path, false, Encoding.GetEncoding(encoding)))
            {
                writer.Write(str);
            }
        }

        private static string Join(this IEnumerable<string> list, string delimiter = ",")
        {
            return string.Join(delimiter, list.ToArray());
        }

        private static MatchCollection RegexMatches(
            this string str, string pattern, RegexOptions regexOptions)
        {
            return Regex.Matches(str, pattern, regexOptions);
        }

        private static void Append(this StringBuilder stringBuilder, params string[] strings)
        {
            strings.ForEach(str => stringBuilder.Append(str));
        }

        private static string Params(this string format, params object[] args)
        {
            return string.Format(format, args);
        }

        private static string[] SplitReturn(this string str)
        {
            return str.Replace("\r\n", "\n").Split('\n');
        }
    }
}

Program.cs

using System.Data.SqlClient;
namespace Implem.Sample
{
    class Program
    {
        static void Main(string[] args)
        {
            var cmd = new SqlCommand("select [abc].[a], [abc].[b], [abc].[c], [abc].[d], [abc].[e] from [abc] where @p1");
            cmd.Parameters.AddWithValue("p1", "hoge");
            Debugs.WriteCommandTextForDebugging("dbname", cmd);
        }
    }
}