Sqlite创建增删改查

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.SQLite;
using System.Data.Common;
using System.IO;


namespace SqliteDemo
{
    public partial class Form1 : Form
    {

        
        public Form1()
        {
            InitializeComponent();
        }
        
        
        string sqlitePath = Application.StartupPath + "/test.db";
        System.Data.SQLite.SQLiteConnection conn = new System.Data.SQLite.SQLiteConnection();
        System.Data.SQLite.SQLiteCommand cmd = new System.Data.SQLite.SQLiteCommand();
        string sql;
        
        /// <summary>
        /// 创建数据库
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnCreat_Click(object sender, EventArgs e)
        {
            if (File.Exists(sqlitePath))
            {
                MessageBox.Show("数据库已经存在","error",MessageBoxButtons.OK,MessageBoxIcon.Error);
            }
            else
            {
                try
                {   
                    //创建一个数据库文件
                    System.Data.SQLite.SQLiteConnection.CreateFile(sqlitePath);
                }
                catch (Exception ex)
                {
                    MessageBox.Show("创建数据库失败" + ex.ToString()); 
                } 
            } 
        }
        
        private void btnConnect_Click(object sender, EventArgs e)
        {
            //连接数据库
            
            try{
                System.Data.SQLite.SQLiteConnectionStringBuilder connstr = new System.Data.SQLite.SQLiteConnectionStringBuilder();
                connstr.DataSource = sqlitePath;
                //connstr.Password = "admin";//设置密码，SQLite ADO.NET实现了数据库密码保护
                conn.ConnectionString = connstr.ToString();
                conn.Open();
                cmd.Connection = conn;
            }
       
            catch (Exception ex)
            {
                MessageBox.Show("连接数据库" + ex.ToString());
            }
        }

        private void btnCreatTable_Click(object sender, EventArgs e)
        {
            try
            {
                //创建表
                sql = "CREATE TABLE test(username varchar(20),password varchar(20))";
                cmd.CommandText = sql;
                cmd.Connection = conn;
                cmd.ExecuteNonQuery();
            }
            catch (Exception ex)
            {
                MessageBox.Show("创建表失败" + ex.ToString()); 
            }
        }
        private void btnAdd_Click(object sender, EventArgs e)
        {
            try
            {
                sql = "insert into  test (username,password) values (‘" + "123" + "‘,‘" + "456" + "‘)";
                cmd.CommandText = sql;
                cmd.ExecuteNonQuery();
            }
            catch (Exception ex)
            {
                MessageBox.Show("增加失败" + ex.ToString());
            }
        }

        private void btnSelect_Click(object sender, EventArgs e)
        {
            try
            {
                listView1.Items.Clear();
                sql = "SELECT * FROM test";
                cmd.CommandText = sql;
                System.Data.SQLite.SQLiteDataReader reader = cmd.ExecuteReader();

                while (reader.Read())
                {
                    ListViewItem lvi = new ListViewItem();
                    lvi.Text = (listView1.Items.Count + 1).ToString();
                    lvi.SubItems.Add(reader.GetString(0));
                    lvi.SubItems.Add(reader.GetString(1));
                    listView1.Items.Add(lvi);
                }
                reader.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show("读取失败" + ex.ToString());
            }
        }

        private void btnDeleteAll_Click(object sender, EventArgs e)
        {
            sql = "delete FROM test";
            cmd.CommandText = sql;
            cmd.ExecuteNonQuery();
        }

        private void btnDelete_Click(object sender, EventArgs e)
        {

            sql = "DELETE FROM test WHERE username = ‘"+textBox1.Text.Trim()+"‘";
            cmd.CommandText = sql;

            cmd.ExecuteNonQuery();
        }
      
    }
}