using System;

using Microsoft.VisualBasic;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine(SQLCharCheck("'test string1'"));

        Console.WriteLine(SQLCharCheck("'test string2"));

        Console.WriteLine(SQLCharCheck("test string3'"));

        Console.WriteLine(SQLCharCheck("test string'4"));

        Console.WriteLine(SQLCharCheck("test''''''' st-----ri*/n*/g5"));

        Console.WriteLine(SQLCharCheck("test''''''' st-----ri*/n*/g6'"));

    }

​

    public static object SQLCharCheck(string Value, bool incQuotes = true)

    {

        bool containsQuote = false;

        try

        {

            if (!object.ReferenceEquals(Value, DBNull.Value))

            {

                if (Value.Contains("'"))

                    containsQuote = true;

                while (Value.Contains("''"))

                    Value = Value.Replace("''", "'");

                while (Value.Contains("--"))

                    Value = Value.Replace("--", "");

                while (Value.Contains("/*"))

                    Value = Value.Replace("/*", "");

                while (Value.Contains("*/"))

                    Value = Value.Replace("*/", "");

                if (string.IsNullOrEmpty(Value.Trim()))

                    Value = "NULL";

            }

            else

            {

                Value = "NULL";

                return Value;

            }

        }

        catch

        {

        }

​

        if (!(Value.StartsWith("'") && Value.EndsWith("'")) && Value.ToUpper() != "NULL")

        {

            if (incQuotes)

                Value = FixQuotes(Value);

        }

​

        return Value;

    }

​

    public static string FixQuotes(string sLine)

        {

            string s = sLine.ToString();

            int i = 0;

            int j = 0;

            i = 1;

            j = Strings.InStr(i, s, @"'");

            while (!(j == 0))

            {

                s = Strings.Left(s, j) + Strings.Mid(s, j);

                i = j + 2;

                j = Strings.InStr(i, s, @"'");

            }

            return "'" + Strings.Trim(s) + "'";

​

        }

}