Factory/FormLevin.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace СУБД_Фабрика
{
    public partial class FormLevin : Form
    {
        public FormLevin()
        {
            InitializeComponent();
        }

        SqlConnection Con = new SqlConnection(FormMain.txtCon); 

        List<string> LstTitle = new List<string>();

        static int Levenshtein(string text1, string text2)
        {
            int CntLev = Math.Abs(text1.Length - text2.Length);
            for (int i = 0; i <= Math.Min(text1.Length, text2.Length) - 1; i++)
            {
                if (text1[i] != text2[i])
                    CntLev++;
            }
            return CntLev;
        }

        private void FormLevin_Load(object sender, EventArgs e)
        {
            string txtQuery = "select Title from Cloth";
            Con.Open();
            SqlCommand query = new SqlCommand(txtQuery, Con);
            SqlDataReader Res = query.ExecuteReader();
            while(Res.Read())
            {
                LstTitle.Add(Res["Title"].ToString());
            }
            Con.Close();
            BtnShowAll_Click(sender, e);
        }

        private void BtnShowAll_Click(object sender, EventArgs e)
        {
            DgvClothes.Rows.Clear();
            foreach (string title in LstTitle)
                DgvClothes.Rows.Add(title);
        }

        private void BtnLeven_Click(object sender, EventArgs e)
        {
            DgvClothes.Rows.Clear();
            foreach(string title in LstTitle)
            {
                if(Levenshtein(title, TbxLeven.Text) <= 3)
                {
                    DgvClothes.Rows.Add(title);
                }
            }
        }
    }
}