using System;

using System.Text.RegularExpressions;

​

public class Program

{

    private static readonly string[] ValidSQLStatementPattern = new string[] { "SELECT ", "CREATE TEMPORARY ", "DROP TEMPORARY " };

    private const string Semicolon = ";";

    private static Regex SemicolonRegeEx = new Regex("\'.*?;.*?\'", RegexOptions.Compiled);

​

    public static void Main()

    {

        //

        string temp = "DELETE FROM xyz; TRUNCATE TABLE xyz; INSERT INTO XYZ; UPDATE XYZ SET z=1;SELECT * FROM abc where abc like '% ; %';";

        //string temp = "DELETE FROM t";

        Console.WriteLine(IsValidSQL(temp));

    }

​

    private static int CountStringOccurrences(string inputText, string inputPattern)

    {

        int count = 0;

        int i = 0;

        while ((i = inputText.IndexOf(inputPattern, i, StringComparison.InvariantCultureIgnoreCase)) != -1)

        {

            i += inputPattern.Length;

            count++;

        }

​

        return count;

    }

​

    private static bool IsValidSQL(string inputString)

    {

        bool isValid = false;

        int semicolonCount = CountSemicolons(inputString);

        if (semicolonCount > 0)

        {

            isValid = (CountValidStatements(inputString) == semicolonCount);

        }

        return isValid;

    }

    private static int CountValidStatements(string inputString)

    {

        int count = 0;

        foreach(string pattern in ValidSQLStatementPattern)

        {

            count+= CountStringOccurrences(inputString, pattern);

        }

        return count;

    }

    private static int CountSemicolons(string inputString)

    {

        int count = 0;

        count= CountStringOccurrences(inputString, Semicolon) - SemicolonRegeEx.Matches(inputString).Count;     

        return count;

    }

}