【Unity MySQL小白教程④】增删改查完整实现与DAO封装

前言

上一篇跑通了第一个查询。本篇把增、删、改、查四种操作全部实现，并封装成一个可复用的 PlayerDao 类。学完这篇，你就拥有了一个生产级的数据访问层模板，后续所有表都可以照着这个模式复制。

一、实体类定义

先定义与数据库表对应的C#实体：

// Assets/Scripts/Models/PlayerEntity.cs
using System;

[Serializable]
public class PlayerEntity
{
    public long Id;
    public string Username;
    public string Nickname;
    public string Email;
    public int Level;
    public long Exp;
    public long Gold;
    public int Diamond;
    public int AvatarId;
    public int Status;
    public DateTime CreatedAt;
    public DateTime UpdatedAt;
}

💡 实体类用纯字段而非属性，方便后续序列化。[Serializable] 让它在Inspector中可见（调试用）。

二、数据库管理器单例

所有DAO共享同一个连接字符串和连接池配置：

// Assets/Scripts/Data/DatabaseManager.cs
using MySqlConnector;
using UnityEngine;

public class DatabaseManager : MonoBehaviour
{
    private static DatabaseManager _instance;
    public static DatabaseManager Instance => _instance;

    [SerializeField] private DatabaseConfig _config;

    private void Awake()
    {
        if (_instance != null && _instance != this) { Destroy(gameObject); return; }
        _instance = this;
        DontDestroyOnLoad(gameObject);
    }

    /// <summary>创建新连接（连接池自动复用底层TCP）</summary>
    public MySqlConnection CreateConnection()
    {
        return new MySqlConnection(_config.ConnectionString);
    }
}

三、PlayerDao 完整实现

3.1 CREATE — 新增玩家

// Assets/Scripts/Data/PlayerDao.cs
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using MySqlConnector;
using UnityEngine;

public static class PlayerDao
{
    /// <summary>新增玩家，返回自增ID</summary>
    public static async Task<long> InsertAsync(PlayerEntity player)
    {
        const string sql = @"INSERT INTO players 
            (username, nickname, email, password_hash, level, exp, gold, diamond, avatar_id, status)
            VALUES (@username, @nickname, @email, @pwdHash, @level, @exp, @gold, @diamond, @avatarId, @status)";

        using var conn = DatabaseManager.Instance.CreateConnection();
        await conn.OpenAsync();

        using var cmd = conn.CreateCommand();
        cmd.CommandText = sql;
        cmd.Parameters.AddWithValue("@username", player.Username);
        cmd.Parameters.AddWithValue("@nickname", player.Nickname);
        cmd.Parameters.AddWithValue("@email", (object)player.Email ?? DBNull.Value);
        cmd.Parameters.AddWithValue("@pwdHash", BCrypt.Net.BCrypt.HashPassword("default123"));
        cmd.Parameters.AddWithValue("@level", player.Level);
        cmd.Parameters.AddWithValue("@exp", player.Exp);
        cmd.Parameters.AddWithValue("@gold", player.Gold);
        cmd.Parameters.AddWithValue("@diamond", player.Diamond);
        cmd.Parameters.AddWithValue("@avatarId", player.AvatarId);
        cmd.Parameters.AddWithValue("@status", player.Status);

        await cmd.ExecuteNonQueryAsync();
        return cmd.LastInsertedId;
    }
}

⚠️ 密码永远不要明文存储！ 这里用BCrypt哈希。实际项目中密码应由服务端处理，客户端不接触明文密码。

3.2 READ — 查询单个 + 查询列表

/// <summary>根据ID查询玩家</summary>
public static async Task<PlayerEntity> GetByIdAsync(long id)
{
    const string sql = "SELECT * FROM players WHERE id = @id LIMIT 1";

    using var conn = DatabaseManager.Instance.CreateConnection();
    await conn.OpenAsync();

    using var cmd = conn.CreateCommand();
    cmd.CommandText = sql;
    cmd.Parameters.AddWithValue("@id", id);

    using var reader = await cmd.ExecuteReaderAsync();
    if (!await reader.ReadAsync()) return null;

    return MapToEntity(reader);
}

/// <summary>分页查询玩家列表</summary>
public static async Task<List<PlayerEntity>> GetListAsync(int page, int pageSize, string orderBy = "level DESC")
{
    // ⚠️ orderBy来自代码常量，不接受用户输入，防止SQL注入
    string sql = $"SELECT * FROM players ORDER BY {orderBy} LIMIT @limit OFFSET @offset";

    using var conn = DatabaseManager.Instance.CreateConnection();
    await conn.OpenAsync();

    using var cmd = conn.CreateCommand();
    cmd.CommandText = sql;
    cmd.Parameters.AddWithValue("@limit", pageSize);
    cmd.Parameters.AddWithValue("@offset", (page - 1) * pageSize);

    var list = new List<PlayerEntity>();
    using var reader = await cmd.ExecuteReaderAsync();
    while (await reader.ReadAsync())
        list.Add(MapToEntity(reader));

    return list;
}

/// <summary>DataReader → Entity 映射</summary>
private static PlayerEntity MapToEntity(MySqlDataReader r)
{
    return new PlayerEntity
    {
        Id = r.GetInt64("id"),
        Username = r.GetString("username"),
        Nickname = r.GetString("nickname"),
        Email = r.IsDBNull(r.GetOrdinal("email")) ? null : r.GetString("email"),
        Level = r.GetInt32("level"),
        Exp = r.GetInt64("exp"),
        Gold = r.GetInt64("gold"),
        Diamond = r.GetInt32("diamond"),
        AvatarId = r.GetInt32("avatar_id"),
        Status = r.GetInt32("status"),
        CreatedAt = r.GetDateTime("created_at"),
        UpdatedAt = r.GetDateTime("updated_at"),
    };
}

3.3 UPDATE — 更新玩家信息

/// <summary>更新玩家基础信息，返回影响行数</summary>
public static async Task<int> UpdateAsync(PlayerEntity player)
{
    const string sql = @"UPDATE players SET 
        nickname=@nickname, email=@email, level=@level, exp=@exp,
        gold=@gold, diamond=@diamond, avatar_id=@avatarId, status=@status
        WHERE id=@id";

    using var conn = DatabaseManager.Instance.CreateConnection();
    await conn.OpenAsync();

    using var cmd = conn.CreateCommand();
    cmd.CommandText = sql;
    cmd.Parameters.AddWithValue("@id", player.Id);
    cmd.Parameters.AddWithValue("@nickname", player.Nickname);
    cmd.Parameters.AddWithValue("@email", (object)player.Email ?? DBNull.Value);
    cmd.Parameters.AddWithValue("@level", player.Level);
    cmd.Parameters.AddWithValue("@exp", player.Exp);
    cmd.Parameters.AddWithValue("@gold", player.Gold);
    cmd.Parameters.AddWithValue("@diamond", player.Diamond);
    cmd.Parameters.AddWithValue("@avatarId", player.AvatarId);
    cmd.Parameters.AddWithValue("@status", player.Status);

    return await cmd.ExecuteNonQueryAsync();
}

3.4 DELETE — 删除玩家

/// <summary>逻辑删除（推荐）：将status设为3</summary>
public static async Task<int> SoftDeleteAsync(long id)
{
    const string sql = "UPDATE players SET status=3 WHERE id=@id";

    using var conn = DatabaseManager.Instance.CreateConnection();
    await conn.OpenAsync();

    using var cmd = conn.CreateCommand();
    cmd.CommandText = sql;
    cmd.Parameters.AddWithValue("@id", id);

    return await cmd.ExecuteNonQueryAsync();
}

/// <summary>物理删除（慎用）</summary>
public static async Task<int> HardDeleteAsync(long id)
{
    const string sql = "DELETE FROM players WHERE id=@id";

    using var conn = DatabaseManager.Instance.CreateConnection();
    await conn.OpenAsync();

    using var cmd = conn.CreateCommand();
    cmd.CommandText = sql;
    cmd.Parameters.AddWithValue("@id", id);

    return await cmd.ExecuteNonQueryAsync();
}

💡 生产环境优先用逻辑删除。物理删除会导致外键级联、审计丢失、误操作不可恢复。

四、在Unity中调用

// Assets/Scripts/UI/PlayerPanel.cs
using System.Collections.Generic;
using UnityEngine;

public class PlayerPanel : MonoBehaviour
{
    private async void Start()
    {
        // 查
        var players = await PlayerDao.GetListAsync(page: 1, pageSize: 10);
        foreach (var p in players)
            Debug.Log($"[{p.Id}] {p.Nickname} Lv.{p.Level}");

        // 增
        var newPlayer = new PlayerEntity
        {
            Username = "newbie001",
            Nickname = "新手冒险者",
            Level = 1, Gold = 1000, Diamond = 10,
            AvatarId = 1, Status = 1
        };
        long newId = await PlayerDao.InsertAsync(newPlayer);
        Debug.Log($"新建玩家ID: {newId}");

        // 改
        newPlayer.Id = newId;
        newPlayer.Gold = 5000;
        int rows = await PlayerDao.UpdateAsync(newPlayer);
        Debug.Log($"更新影响行数: {rows}");

        // 删（逻辑删除）
        int delRows = await PlayerDao.SoftDeleteAsync(newId);
        Debug.Log($"删除影响行数: {delRows}");
    }
}

五、CRUD安全Checklist

检查项	说明
✅ 全部使用参数化查询	零字符串拼接SQL
✅ 密码BCrypt哈希存储	永不明文
✅ 异步操作不阻塞主线程	全部async/await
✅ using管理连接生命周期	自动归还连接池
✅ NULL值用DBNull.Value	避免NullReferenceException
✅ 逻辑删除优先于物理删除	数据安全兜底
✅ orderBy白名单校验	防排序字段注入
✅ 分页LIMIT/OFFSET参数化	防越界查询

六、性能优化提示

场景	优化手段
批量插入100+条	使用事务包裹 + MySqlBulkCopy
高频读取同一数据	加内存缓存(Dictionary + TTL)
大表分页慢	改用游标分页(WHERE id > @lastId)替代OFFSET
统计查询慢	加覆盖索引或预计算汇总表
并发写入冲突	乐观锁(version字段)或悲观锁(SELECT FOR UPDATE)

总结

本篇实现了完整的CRUD四件套：Insert返回自增ID、GetById+分页列表、Update影响行数、SoftDelete逻辑删除。核心原则只有两个：参数化查询保安全、async/await保流畅。把这个模板吃透，换任何表都能快速复刻。

下一篇我们跳出客户端直连，搭建HTTP API中间层，这才是生产环境的正确姿势。

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