C#操作SQLite实现数据的增删改查

Tanya ·

更新时间:2024-11-13

· 506 次阅读

简介

主要代码

SQLiteHelper.cs

UsingLock.cs

Form1.cs

简介

SQLite是一个轻量级、跨平台的关系型数据库，在小型项目中，方便，易用，同时支持多种开发语言，下面是我用C#语言对SQLite 的一个封装。

Winfrom界面如下：

代码还需要改进部分：

下面的代码我不觉得是完美的，读者可以自己去实现这些功能：

1.如果不想用多线程可以去掉UsingLock.cs ，在SQLiteHelper.cs中删除对应的引用即可。

2.创建数据库文件，可以从代码中分离成单独的方法。比如创建有密码的数据库文件。

3.在执行SQL语句时，有些语句执行成功，也不会有影响行数。比如，创建表，删除表，此时执行SQL语句返回的影响行数就为0。

4.只要SQL语句不报错就是执行成功的，在方法的返回值可以改为多个，比如用

Tuple<bool, string, int> 第一个参数 bool 代表执行结果，第二个参数 string 代表错误信息，第三个参数 int 代表影响的行数。

同样，也可以这样：

Tuple<bool, string, DataSet> 第一个参数 bool 代表执行结果，第二个参数 string 代表错误信息，第三个参数 DataSet 代表返回的表单数据。

主要代码 SQLiteHelper.cs

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.Data.SQLite;
using System.IO;
using System.Text;
namespace MySQLiteHelper
{
    public class SQLiteHelper
    {
        #region 字段
        /// <summary>
        /// 事务的基类
        /// </summary>
        private DbTransaction DBtrans;
        /// <summary>
        /// 使用静态变量字典解决多线程实例本类，实现一个数据库对应一个clslock
        /// </summary>
        private static readonly Dictionary<string, ClsLock> RWL = new Dictionary<string, ClsLock>();
        /// <summary>
        /// 数据库地址
        /// </summary>
        private readonly string mdataFile;
        /// <summary>
        /// 数据库密码
        /// </summary>
        private readonly string mPassWord;
        private readonly string LockName = null;
        /// <summary>
        /// 数据库连接定义
        /// </summary>
        private SQLiteConnection mConn;
        #endregion
        #region 构造函数
        /// <summary>
        /// 根据数据库地址初始化
        /// </summary>
        /// <param name="dataFile">数据库地址</param>
        public SQLiteHelper(string dataFile)
        {
            this.mdataFile = dataFile ?? throw new ArgumentNullException("dataFile=null");
            //this.mdataFile = AppDomain.CurrentDomain.BaseDirectory + dataFile;
            this.mdataFile = dataFile;
            if (!RWL.ContainsKey(dataFile))
            {
                LockName = dataFile;
                RWL.Add(dataFile, new ClsLock());
            }
        }
        /// <summary>
        /// 使用密码打开数据库
        /// </summary>
        /// <param name="dataFile">数据库地址</param>
        /// <param name="PassWord">数据库密码</param>
        public SQLiteHelper(string dataFile, string PassWord)
        {
            this.mdataFile = dataFile ?? throw new ArgumentNullException("dataFile is null");
            this.mPassWord = PassWord ?? throw new ArgumentNullException("PassWord is null");
            //this.mdataFile = AppDomain.CurrentDomain.BaseDirectory + dataFile;
            this.mdataFile = dataFile;
            if (!RWL.ContainsKey(dataFile))
            {
                LockName = dataFile;
                RWL.Add(dataFile, new ClsLock());
            }
        }
        #endregion
        #region 打开/关闭 数据库
        /// <summary>  
        /// 打开 SQLiteManager 使用的数据库连接  
        /// </summary>  
        public void Open()
        {
            if (string.IsNullOrWhiteSpace(mPassWord))
            {
                mConn = OpenConnection(this.mdataFile);
            }
            else
            {
                mConn = OpenConnection(this.mdataFile, mPassWord);
            }
            Console.WriteLine("打开数据库成功");
        }
        /// <summary>
        /// 关闭连接
        /// </summary>
        public void Close()
        {
            if (this.mConn != null)
            {
                try
                {
                    this.mConn.Close();
                    if (RWL.ContainsKey(LockName))
                    {
                        RWL.Remove(LockName);
                    }
                }
                catch
                {
                    Console.WriteLine("关闭失败");
                }
            }
            Console.WriteLine("关闭数据库成功");
        }
        #endregion
        #region 事务
        /// <summary>
        /// 开始事务
        /// </summary>
        public void BeginTrain()
        {
            EnsureConnection();
            DBtrans = mConn.BeginTransaction();
        }
        /// <summary>
        /// 提交事务
        /// </summary>
        public void DBCommit()
        {
            try
            {
                DBtrans.Commit();
            }
            catch (Exception)
            {
                DBtrans.Rollback();
            }
        }
        #endregion
        #region 工具
        /// <summary>  
        /// 打开一个SQLite数据库文件，如果文件不存在，则创建（无密码）
        /// </summary>  
        /// <param name="dataFile"></param>  
        /// <returns>SQLiteConnection 类</returns>  
        private SQLiteConnection OpenConnection(string dataFile)
        {
            if (dataFile == null)
            {
                throw new ArgumentNullException("dataFiledataFile=null");
            }
            if (!File.Exists(dataFile))
            {
                SQLiteConnection.CreateFile(dataFile);
            }
            SQLiteConnection conn = new SQLiteConnection();
            SQLiteConnectionStringBuilder conStr = new SQLiteConnectionStringBuilder
            {
                DataSource = dataFile
            };
            conn.ConnectionString = conStr.ToString();
            conn.Open();
            return conn;
        }
        /// <summary>  
        /// 打开一个SQLite数据库文件，如果文件不存在，则创建（有密码）
        /// </summary>  
        /// <param name="dataFile"></param>  
        /// <param name="Password"></param>
        /// <returns>SQLiteConnection 类</returns>  
        private SQLiteConnection OpenConnection(string dataFile, string Password)
        {
            if (dataFile == null)
            {
                throw new ArgumentNullException("dataFile=null");
            }
            if (!File.Exists(Convert.ToString(dataFile)))
            {
                SQLiteConnection.CreateFile(dataFile);
            }
            try
            {
                SQLiteConnection conn = new SQLiteConnection();
                SQLiteConnectionStringBuilder conStr = new SQLiteConnectionStringBuilder
                {
                    DataSource = dataFile,
                    Password = Password
                };
                conn.ConnectionString = conStr.ToString();
                conn.Open();
                return conn;
            }
            catch (Exception)
            {
                return null;
            }
        }
        /// <summary>  
        /// 读取 或 设置 SQLiteManager 使用的数据库连接  
        /// </summary>  
        public SQLiteConnection Connection
        {
            get
            {
                return mConn;
            }
            private set
            {
                mConn = value ?? throw new ArgumentNullException();
            }
        }
        /// <summary>
        /// 确保数据库是连接状态
        /// </summary>
        /// <exception cref="Exception"></exception>
        protected void EnsureConnection()
        {
            if (this.mConn == null)
            {
                throw new Exception("SQLiteManager.Connection=null");
            }
            if (mConn.State != ConnectionState.Open)
            {
                mConn.Open();
            }
        }
        /// <summary>
        /// 获取数据库文件的路径
        /// </summary>
        /// <returns></returns>
        public string GetDataFile()
        {
            return this.mdataFile;
        }
        /// <summary>  
        /// 判断表 table 是否存在  
        /// </summary>  
        /// <param name="table"></param>  
        /// <returns>存在返回true，否则返回false</returns>  
        public bool TableExists(string table)
        {
            if (table == null)
            {
                throw new ArgumentNullException("table=null");
            }
            EnsureConnection();
            SQLiteDataReader reader = ExecuteReader("SELECT count(*) as c FROM sqlite_master WHERE type='table' AND name=@tableName ", new SQLiteParameter[] { new SQLiteParameter("tableName", table) });
            if (reader == null)
            {
                return false;
            }
            reader.Read();
            int c = reader.GetInt32(0);
            reader.Close();
            reader.Dispose();
            //return false;  
            return c == 1;
        }
        /// <summary>
        /// VACUUM 命令（通过复制主数据库中的内容到一个临时数据库文件，然后清空主数据库，并从副本中重新载入原始的数据库文件）
        /// </summary>
        /// <returns></returns>
        public bool Vacuum()
        {
            try
            {
                using (SQLiteCommand Command = new SQLiteCommand("VACUUM", Connection))
                {
                    Command.ExecuteNonQuery();
                }
                return true;
            }
            catch (System.Data.SQLite.SQLiteException)
            {
                return false;
            }
        } 
        #endregion
        #region 执行SQL
        /// <summary>
        /// 执行SQL, 并返回 SQLiteDataReader 对象结果 
        /// </summary>  
        /// <param name="sql"></param>
        /// <param name="paramArr">null 表示无参数</param>
        /// <returns></returns>  
        public SQLiteDataReader ExecuteReader(string sql, SQLiteParameter[] paramArr)
        {
            if (sql == null)
            {
                throw new ArgumentNullException("sql=null");
            }
            EnsureConnection();
            using (RWL[LockName].Read())
            {
                using (SQLiteCommand cmd = new SQLiteCommand(sql, Connection))
                {
                    if (paramArr != null)
                    {
                        cmd.Parameters.AddRange(paramArr);
                    }
                    try
                    {
                        SQLiteDataReader reader = cmd.ExecuteReader();
                        cmd.Parameters.Clear();
                        return reader;
                    }
                    catch (Exception)
                    {
                        return null;
                    }
                }
            }
        }
        /// <summary>
        /// 执行查询，并返回dataset对象
        /// </summary>
        /// <param name="sql">SQL查询语句</param>
        /// <param name="paramArr">参数数组</param>
        /// <returns></returns>
        public DataSet ExecuteDataSet(string sql, SQLiteParameter[] paramArr)
        {
            if (sql == null)
            {
                throw new ArgumentNullException("sql=null");
            }
            this.EnsureConnection();
            using (RWL[LockName].Read())
            {
                using (SQLiteCommand cmd = new SQLiteCommand(sql, this.Connection))
                {
                    if (paramArr != null)
                    {
                        cmd.Parameters.AddRange(paramArr);
                    }
                    try
                    {
                        SQLiteDataAdapter da = new SQLiteDataAdapter();
                        DataSet ds = new DataSet();
                        da.SelectCommand = cmd;
                        da.Fill(ds);
                        cmd.Parameters.Clear();
                        da.Dispose();
                        return ds;
                    }
                    catch (Exception)
                    {
                        return null;
                    }
                }
            }
        }
        /// <summary>
        /// 执行SQL查询，并返回dataset对象。
        /// </summary>
        /// <param name="strTable">映射源表的名称</param>
        /// <param name="sql">SQL语句</param>
        /// <param name="paramArr">SQL参数数组</param>
        /// <returns></returns>
        public DataSet ExecuteDataSet(string strTable, string sql, SQLiteParameter[] paramArr)
        {
            if (sql == null)
            {
                throw new ArgumentNullException("sql=null");
            }
            this.EnsureConnection();
            using (RWL[LockName].Read())
            {
                using (SQLiteCommand cmd = new SQLiteCommand(sql, this.Connection))
                {
                    if (paramArr != null)
                    {
                        cmd.Parameters.AddRange(paramArr);
                    }
                    try
                    {
                        SQLiteDataAdapter da = new SQLiteDataAdapter();
                        DataSet ds = new DataSet();
                        da.SelectCommand = cmd;
                        da.Fill(ds, strTable);
                        cmd.Parameters.Clear();
                        da.Dispose();
                        return ds;
                    }
                    catch (Exception)
                    {
                        return null;
                    }
                }
            }
        }
        /// <summary>  
        /// 执行SQL，返回受影响的行数，可用于执行表创建语句，paramArr == null 表示无参数
        /// </summary>  
        /// <param name="sql"></param>  
        /// <returns></returns>  
        public int ExecuteNonQuery(string sql, SQLiteParameter[] paramArr)
        {
            if (sql == null)
            {
                throw new ArgumentNullException("sql=null");
            }
            this.EnsureConnection();
            using (RWL[LockName].Read())
            {
                try
                {
                    using (SQLiteCommand cmd = new SQLiteCommand(sql, Connection))
                    {
                        if (paramArr != null)
                        {
                            foreach (SQLiteParameter p in paramArr)
                            {
                                cmd.Parameters.Add(p);
                            }
                        }
                        int c = cmd.ExecuteNonQuery();
                        cmd.Parameters.Clear();
                        return c;
                    }
                }
                catch (SQLiteException)
                {
                    return 0;
                }
            }
        }
        /// <summary>  
        /// 执行SQL，返回结果集第一行，如果结果集为空，那么返回空 List(List.Count=0)， 
        /// rowWrapper = null 时，使用 WrapRowToDictionary  
        /// </summary>  
        /// <param name="sql"></param>  
        /// <param name="paramArr"></param>  
        /// <returns></returns>  
        public object ExecuteScalar(string sql, SQLiteParameter[] paramArr)
        {
            if (sql == null)
            {
                throw new ArgumentNullException("sql=null");
            }
            this.EnsureConnection();
            using (RWL[LockName].Read())
            {
                using (SQLiteCommand cmd = new SQLiteCommand(sql, Connection))
                {
                    if (paramArr != null)
                    {
                        cmd.Parameters.AddRange(paramArr);
                    }
                    try
                    {
                        object reader = cmd.ExecuteScalar();
                        cmd.Parameters.Clear();
                        cmd.Dispose();
                        return reader;
                    }
                    catch (Exception)
                    {
                        return null;
                    }
                }
            }
        }
        /// <summary>  
        /// 查询一行记录，无结果时返回 null，conditionCol = null 时将忽略条件，直接执行 select * from table   
        /// </summary>  
        /// <param name="table">表名</param>  
        /// <param name="conditionCol"></param>  
        /// <param name="conditionVal"></param>  
        /// <returns></returns>  
        public object QueryOne(string table, string conditionCol, object conditionVal)
        {
            if (table == null)
            {
                throw new ArgumentNullException("table=null");
            }
            this.EnsureConnection();
            string sql = "select * from " + table;
            if (conditionCol != null)
            {
                sql += " where " + conditionCol + "=@" + conditionCol;
            }
            object result = ExecuteScalar(sql, new SQLiteParameter[] { new SQLiteParameter(conditionCol, conditionVal) });
            return result;
        }
        #endregion
        #region 增 删 改
        /// <summary>  
        /// 执行 insert into 语句 
        /// </summary>  
        /// <param name="table"></param>  
        /// <param name="entity"></param>  
        /// <returns></returns>  
        public int InsertData(string table, Dictionary<string, object> entity)
        {
            if (table == null)
            {
                throw new ArgumentNullException("table=null");
            }
            this.EnsureConnection();
            string sql = BuildInsert(table, entity);
            return this.ExecuteNonQuery(sql, BuildParamArray(entity));
        }
        /// <summary>  
        /// 执行 update 语句，注意：如果 where = null，那么 whereParams 也为 null，
        /// </summary>  
        /// <param name="table">表名</param>  
        /// <param name="entity">要修改的列名和列名的值</param>  
        /// <param name="where">查找符合条件的列</param>  
        /// <param name="whereParams">where条件中参数的值</param>  
        /// <returns></returns>  
        public int Update(string table, Dictionary<string, object> entity, string where, SQLiteParameter[] whereParams)
        {
            if (table == null)
            {
                throw new ArgumentNullException("table=null");
            }
            this.EnsureConnection();
            string sql = BuildUpdate(table, entity);
            SQLiteParameter[] parameter = BuildParamArray(entity);
            if (where != null)
            {
                sql += " where " + where;
                if (whereParams != null)
                {
                    SQLiteParameter[] newArr = new SQLiteParameter[(parameter.Length + whereParams.Length)];
                    Array.Copy(parameter, newArr, parameter.Length);
                    Array.Copy(whereParams, 0, newArr, parameter.Length, whereParams.Length);
                    parameter = newArr;
                }
            }
            return this.ExecuteNonQuery(sql, parameter);
        }
        /// <summary>  
        /// 执行 delete from table 语句，where不必包含'where'关键字，where = null 时将忽略 whereParams  
        /// </summary>  
        /// <param name="table"></param>  
        /// <param name="where"></param>  
        /// <param name="whereParams"></param>  
        /// <returns></returns>  
        public int Delete(string table, string where, SQLiteParameter[] whereParams)
        {
            if (table == null)
            {
                throw new ArgumentNullException("table=null");
            }
            this.EnsureConnection();
            string sql = "delete from " + table + " ";
            if (where != null)
            {
                sql += "where " + where;
            }
            return ExecuteNonQuery(sql, whereParams);
        }
        /// <summary>
        /// 将 Dictionary 类型数据 转换为 SQLiteParameter[] 类型
        /// </summary>
        /// <param name="entity"></param>
        /// <returns></returns>
        private SQLiteParameter[] BuildParamArray(Dictionary<string, object> entity)
        {
            List<SQLiteParameter> list = new List<SQLiteParameter>();
            foreach (string key in entity.Keys)
            {
                list.Add(new SQLiteParameter(key, entity[key]));
            }
            if (list.Count == 0)
            {
                return null;
            }
            return list.ToArray();
        }
        /// <summary>
        /// 将 Dictionary 类型数据 转换为 插入数据 的 SQL语句
        /// </summary>
        /// <param name="table">表名</param>
        /// <param name="entity">字典</param>
        /// <returns></returns>
        private string BuildInsert(string table, Dictionary<string, object> entity)
        {
            StringBuilder buf = new StringBuilder();
            buf.Append("insert into ").Append(table);
            buf.Append(" (");
            foreach (string key in entity.Keys)
            {
                buf.Append(key).Append(",");
            }
            buf.Remove(buf.Length - 1, 1); // 移除最后一个,
            buf.Append(") ");
            buf.Append("values(");
            foreach (string key in entity.Keys)
            {
                buf.Append("@").Append(key).Append(","); // 创建一个参数
            }
            buf.Remove(buf.Length - 1, 1);
            buf.Append(") ");
            return buf.ToString();
        }
        /// <summary>
        /// 将 Dictionary 类型数据 转换为 修改数据 的 SQL语句
        /// </summary>
        /// <param name="table">表名</param>
        /// <param name="entity">字典</param>
        /// <returns></returns>
        private string BuildUpdate(string table, Dictionary<string, object> entity)
        {
            StringBuilder buf = new StringBuilder();
            buf.Append("update ").Append(table).Append(" set ");
            foreach (string key in entity.Keys)
            {
                buf.Append(key).Append("=").Append("@").Append(key).Append(",");
            }
            buf.Remove(buf.Length - 1, 1);
            buf.Append(" ");
            return buf.ToString();
        }
        #endregion
    }
}

UsingLock.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
namespace MySQLiteHelper
{
    /// <summary>
    /// 使用using代替lock操作的对象，可指定写入和读取锁定模式
    /// </summary>
    public sealed class ClsLock
    {
        #region 内部类
        /// <summary>
        /// 利用IDisposable的using语法糖方便的释放锁定操作内部类
        /// </summary>
        private struct Lock : IDisposable
        {
            /// <summary>
            /// 读写锁对象
            /// </summary>
            private readonly ReaderWriterLockSlim _Lock;
            /// <summary>
            /// 是否为写入模式
            /// </summary>
            private bool _IsWrite;
            /// <summary>
            /// 利用IDisposable的using语法糖方便的释放锁定操作构造函数
            /// </summary>
            /// <param name="rwl">读写锁</param>
            /// <param name="isWrite">写入模式为true，读取模式为false</param>
            public Lock(ReaderWriterLockSlim rwl, bool isWrite)
            {
                _Lock = rwl;
                _IsWrite = isWrite;
            }
            /// <summary>
            /// 释放对象时退出指定锁定模式
            /// </summary>
            public void Dispose()
            {
                if (_IsWrite)
                {
                    if (_Lock.IsWriteLockHeld)
                    {
                        _Lock.ExitWriteLock();
                    }
                }
                else
                {
                    if (_Lock.IsReadLockHeld)
                    {
                        _Lock.ExitReadLock();
                    }
                }
            }
        }
        /// <summary>
        /// 空的可释放对象，免去了调用时需要判断是否为null的问题内部类
        /// </summary>
        private class Disposable : IDisposable
        {
            /// <summary>
            /// 空的可释放对象
            /// </summary>
            public static readonly Disposable Empty = new Disposable();
            /// <summary>
            /// 空的释放方法
            /// </summary>
            public void Dispose() { }
        }
        #endregion
        /// <summary>
        /// 读写锁
        /// </summary>
        private readonly ReaderWriterLockSlim _LockSlim = new ReaderWriterLockSlim();
        /// <summary>
        /// 使用using代替lock操作的对象，可指定写入和读取锁定模式构造函数
        /// </summary>
        public ClsLock()
        {
            Enabled = true;
        }
        /// <summary>
        /// 是否启用，当该值为false时，Read()和Write()方法将返回 Disposable.Empty
        /// </summary>
        public bool Enabled { get; set; }
        /// <summary> 
        /// 进入读取锁定模式，该模式下允许多个读操作同时进行，
        /// 退出读锁请将返回对象释放，建议使用using语块,
        /// Enabled为false时，返回Disposable.Empty，
        /// 在读取或写入锁定模式下重复执行，返回Disposable.Empty;
        /// </summary>
        public IDisposable Read()
        {
            if (Enabled == false || _LockSlim.IsReadLockHeld || _LockSlim.IsWriteLockHeld)
            {
                return Disposable.Empty;
            }
            else
            {
                _LockSlim.EnterReadLock();
                return new Lock(_LockSlim, false);
            }
        }
        /// <summary> 
        /// 进入写入锁定模式,该模式下只允许同时执行一个读操作，
        /// 退出读锁请将返回对象释放，建议使用using语块，
        /// Enabled为false时，返回Disposable.Empty，
        /// 在写入锁定模式下重复执行，返回Disposable.Empty
        /// </summary>
        /// <exception cref="NotImplementedException">读取模式下不能进入写入锁定状态</exception>
        public IDisposable Write()
        {
            if (Enabled == false || _LockSlim.IsWriteLockHeld)
            {
                return Disposable.Empty;
            }
            else if (_LockSlim.IsReadLockHeld)
            {
                throw new NotImplementedException("读取模式下不能进入写入锁定状态");
            }
            else
            {
                _LockSlim.EnterWriteLock();
                return new Lock(_LockSlim, true);
            }
        }
    }
}

Form1.cs

using MySQLiteHelper;
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SQLite;
using System.Windows.Forms;
namespace SQLiteDemo
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private SQLiteHelper SQLiteHelpers = null;
        private const string DBAddress = "D:\\SQLiteData\\test_record.db3";
        private void Form1_Load(object sender, EventArgs e)
        {
            SQLiteHelpers = new SQLiteHelper(DBAddress,"123456");
        }
        /// <summary>
        /// 打开数据库
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Button_OpenDB_Click(object sender, EventArgs e)
        {
            SQLiteHelpers.Open();
            Label_DBOpenState.Text = "打开";
        }
        /// <summary>
        /// 关闭数据库
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Button_CloseDB_Click(object sender, EventArgs e)
        {
            SQLiteHelpers.Close();
            Label_DBOpenState.Text = "关闭";
        }
        /// <summary>
        /// 查询
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Button_Query_Click(object sender, EventArgs e)
        {
            SQLiteParameter[] parameter = new SQLiteParameter[]
            {
                new SQLiteParameter("address", "济南")
            };
            string sql = "SELECT * FROM student WHERE address = @address";
            DataSet dataSet = SQLiteHelpers.ExecuteDataSet(sql, parameter);
            if (dataSet != null)
            {
                dataGridView1.DataSource = dataSet.Tables[0];
            }
        }
        /// <summary>
        /// 插入数据
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Button_Add_Click(object sender, EventArgs e)
        {
            Dictionary<string, object> dic = new Dictionary<string, object>();
            dic.Add("ID", 6);
            dic.Add("name", "王二麻子");
            dic.Add("age", 44);
            dic.Add("address", "陕西");
            int result = SQLiteHelpers.InsertData("student", dic);
            Console.WriteLine("插入结果，受影响的行数：" + result);
        }
        /// <summary>
        /// 修改数据
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Button_Modify_Click(object sender, EventArgs e)
        {
            Dictionary<string, object> dic = new Dictionary<string, object>();
            //将列名 name 的值改为 “猴子”
            dic.Add("name", "猴子");
            //将列名 address 的值改为 花果山
            dic.Add("address", "花果山");
            //where条件
            string where = "ID = @ID AND age = @Age";
            //where条件中对应的参数
            SQLiteParameter[] parameter = new SQLiteParameter[]
            {
                new SQLiteParameter("ID", 4),
                new SQLiteParameter("Age",23)
            };
            int result = SQLiteHelpers.Update("student", dic, where, parameter);
            Console.WriteLine("修改结果，受影响的行数：" + result);
        }
        /// <summary>
        /// 删除数据
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Button_Delete_Click(object sender, EventArgs e)
        {
            //where条件
            string where = "ID = @ID";
            //where条件中对应的参数
            SQLiteParameter[] parameter = new SQLiteParameter[]
            {
                new SQLiteParameter("ID", 6),
            };
            int result = SQLiteHelpers.Delete("student", where, parameter);
            Console.WriteLine("删除结果，受影响的行数：" + result);
        }
        /// <summary>
        /// 判断表是否存在
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Button_TableExists_Click(object sender, EventArgs e)
        {
            string title = "dddd";
            bool result = SQLiteHelpers.TableExists(title);
            Console.WriteLine(string.Format("{0} 表是否存在，结果：{1}", title, result));
        }
        //输出各表中的数据
        //public static void PrintValues(DataSet ds)
        //{
        //    foreach (DataTable table in ds.Tables)
        //    {
        //        Console.WriteLine("表名称：" + table.TableName);
        //        foreach (DataRow row in table.Rows)
        //        {
        //            foreach (DataColumn column in table.Columns)
        //            {
        //                Console.Write(row[column] + "");
        //            }
        //            Console.WriteLine();
        //        }
        //    }
        //}
    }
}

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