I have been trying to implement a regex test for SQL query and would like to create optional parts where if any of these were nulls. I asked someone and mentioned that it is possible to have like nullable ‘?’ in the regex but it seems to fail everytime.

Here is my test:

    [TestMethod]
    public void RegexTest()
    {
        Regex regex = new Regex("SELECT (?<select>.*) from (?<tablename>.*) ((?<jointypecondition>INNER JOIN|LEFT JOIN|RIGHT JOIN|FULL JOIN))? ((?<joincondition>.*))? (WHERE (?<wherecondition>.*))? (ORDER BY (?<ordercondition>.*))?");

        var RegexMatches = regex.Match(ToSearch);

        Assert.IsTrue(regex.IsMatch(ToSearch));

        if (RegexMatches.Success)
        {
            System.Diagnostics.Debug.WriteLine($"Regex Result Columns: {RegexMatches.Groups[1].Value}");
            System.Diagnostics.Debug.WriteLine($"Regex Result Tablename: {RegexMatches.Groups[2].Value}");
            System.Diagnostics.Debug.WriteLine($"Regex Result JoinTypeCondition: {RegexMatches.Groups[3].Value}");
            System.Diagnostics.Debug.WriteLine($"Regex Result JoinCondition: {RegexMatches.Groups[4].Value}");
            System.Diagnostics.Debug.WriteLine($"Regex Result WhereCondition: {RegexMatches.Groups[5].Value}");
            System.Diagnostics.Debug.WriteLine($"Regex Result OrderCondition: {RegexMatches.Groups[6].Value}");
        }

        // Print a success message to the trace
        System.Diagnostics.Debug.WriteLine("Test assertions passed successfully.");
    }

ToSearch => SQL query variable.

Failed Part:

        Assert.IsTrue(regex.IsMatch(ToSearch));

What am I doing wrong here