The class I use in the project is a SQLite database that helps static classes. It can be called directly without using instantiation.
Originally there are a lot of related classes on the Internet. After using a class, you can't call it.

private void TextBox2_TextChanged(object sender, EventArgs e) //新增插入数据
{
SQLiteCommand cmdInsert = new SQLiteCommand(mConn);
string sql = "INSERT INTO KD(postID,ddtime)values(@postID,@ddtime)";
SQLiteParameter[] cmdParms = new SQLiteParameter[]{
new SQLiteParameter("@postID", (textBox2.Text)),
new SQLiteParameter("@ddtime", DateTime.Now)
};
cmd.ExecuteNonQuery(sql,cmdParms);
}

The SQLiteHelper class source is as follows

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.Data.SQLite;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SQLiteQueryBrowser
{
/// /// 本类为SQLite数据库帮助静态类,使用时只需直接调用即可,无需实例化
///
public static class SQLiteHelper
{
/// /// 数据库连接字符串
///
//public static string connectionString = "Data Source=" + Application.StartupPath + "\\" + System.Configuration.ConfigurationSettings.AppSettings["Contr"];
public static string connectionString = "Data Source=" + Application.StartupPath + "/KDDB.db";

    #region 执行数据库操作(新增、更新或删除)，返回影响行数
    /// /// 执行数据库操作(新增、更新或删除)
    /// 
    /// SqlCommand对象
    /// 所受影响的行数
    public static int ExecuteNonQuery(SQLiteCommand cmd)
    {
        int result = 0;
        if (connectionString == null || connectionString.Length == 0)
            throw new ArgumentNullException("connectionString");
        using (SQLiteConnection con = new SQLiteConnection(connectionString))
        {
            SQLiteTransaction trans = null;
            PrepareCommand(cmd, con, ref trans, true, cmd.CommandType, cmd.CommandText);
            try
            {
                result = cmd.ExecuteNonQuery();
                trans.Commit();
            }
            catch (Exception ex)
            {
                trans.Rollback();
                throw ex;
            }
        }