diff --git a/Examples/base_entity/BaseEntity.cs b/Examples/base_entity/BaseEntity.cs
index 018c7d58..84df35b2 100644
--- a/Examples/base_entity/BaseEntity.cs
+++ b/Examples/base_entity/BaseEntity.cs
@@ -2,8 +2,10 @@
 using FreeSql.DataAnnotations;
 using Newtonsoft.Json;
 using System;
+using System.Data;
 using System.Diagnostics;
 using System.Linq.Expressions;
+using System.Threading.Tasks;
 
 [Table(DisableSyncStructure = true)]
 public abstract class BaseEntity
@@ -13,7 +15,7 @@ public abstract class BaseEntity
         var orm = new FreeSqlBuilder()
             .UseAutoSyncStructure(true)
             .UseNoneCommandParameter(true)
-            .UseConnectionString(DataType.Sqlite, "data source=test.db;max pool size=2")
+            .UseConnectionString(DataType.Sqlite, "data source=test.db;max pool size=5")
             //.UseConnectionString(FreeSql.DataType.MySql, "Data Source=127.0.0.1;Port=3306;User ID=root;Password=root;Initial Catalog=cccddd;Charset=utf8;SslMode=none;Max pool size=2")
             //.UseConnectionString(FreeSql.DataType.PostgreSQL, "Host=192.168.164.10;Port=5432;Username=postgres;Password=123456;Database=tedb;Pooling=true;Maximum Pool Size=2")
             //.UseConnectionString(FreeSql.DataType.SqlServer, "Data Source=.;Integrated Security=True;Initial Catalog=freesqlTest;Pooling=true;Max Pool Size=2")
@@ -36,71 +38,108 @@ public abstract class BaseEntity
     /// 逻辑删除
     /// </summary>
     public bool IsDeleted { get; set; }
+
+    /// <summary>
+    /// 开启工作单元事务
+    /// </summary>
+    /// <param name="level"></param>
+    /// <returns></returns>
+    public static IUnitOfWork Begin() => Begin(null);
+    public static IUnitOfWork Begin(IsolationLevel? level)
+    {
+        var uow = new BaseEntityUnitOfWork(Orm);
+        uow.IsolationLevel = level;
+        return uow;
+    }
+    protected static IUnitOfWork CurrentUow => BaseEntityUnitOfWork._asyncUow.Value;
 }
 
 [Table(DisableSyncStructure = true)]
 public abstract class BaseEntity<TEntity> : BaseEntity where TEntity : class
 {
-    public static ISelect<TEntity> Select => Orm.Select<TEntity>().WhereCascade(a => (a as BaseEntity<TEntity>).IsDeleted == false);
+    public static ISelect<TEntity> Select => Orm.Select<TEntity>()
+        .WithTransaction(CurrentUow?.GetOrBeginTransaction(false))
+        .WhereCascade(a => (a as BaseEntity<TEntity>).IsDeleted == false);
     public static ISelect<TEntity> Where(Expression<Func<TEntity, bool>> exp) => Select.Where(exp);
     public static ISelect<TEntity> WhereIf(bool condition, Expression<Func<TEntity, bool>> exp) => Select.WhereIf(condition, exp);
 
     [JsonIgnore]
     protected IBaseRepository<TEntity> Repository { get; set; }
 
-    bool UpdateIsDeleted(bool value)
+    async Task<bool> UpdateIsDeleted(bool value)
     {
         if (this.Repository == null)
-            return Orm.Update<TEntity>(this as TEntity).Set(a => (a as BaseEntity<TEntity>).IsDeleted, this.IsDeleted = value).ExecuteAffrows() == 1;
+            return await Orm.Update<TEntity>(this as TEntity)
+                .WithTransaction(CurrentUow?.GetOrBeginTransaction())
+                .Set(a => (a as BaseEntity<TEntity>).IsDeleted, this.IsDeleted = value).ExecuteAffrowsAsync() == 1;
+
         this.IsDeleted = value;
-        return this.Repository.Update(this as TEntity) == 1;
+        this.Repository.UnitOfWork = CurrentUow;
+        return await this.Repository.UpdateAsync(this as TEntity) == 1;
     }
     /// <summary>
     /// 删除数据
     /// </summary>
     /// <returns></returns>
-    public virtual bool Delete() => this.UpdateIsDeleted(true);
+    public virtual Task<bool> Delete() => this.UpdateIsDeleted(true);
     /// <summary>
     /// 恢复删除的数据
     /// </summary>
     /// <returns></returns>
-    public virtual bool Restore() => this.UpdateIsDeleted(false);
+    public virtual Task<bool> Restore() => this.UpdateIsDeleted(false);
 
     /// <summary>
     /// 附加实体，在更新数据时，只更新变化的部分
     /// </summary>
-    public void Attach()
+    public TEntity Attach()
     {
-        if (this.Repository == null) this.Repository = Orm.GetRepository<TEntity>();
-        this.Repository.Attach(this as TEntity);
+        if (this.Repository == null)
+            this.Repository = Orm.GetRepository<TEntity>();
+
+        var item = this as TEntity;
+        this.Repository.Attach(item);
+        return item;
     }
     /// <summary>
     /// 更新数据
     /// </summary>
     /// <returns></returns>
-    public virtual bool Update()
+    async public virtual Task<bool> Update()
     {
+        this.UpdateTime = DateTime.Now;
         if (this.Repository == null)
-            return Orm.Update<TEntity>().SetSource(this as TEntity).ExecuteAffrows() == 1;
-        return this.Repository.Update(this as TEntity) == 1;
+            return await Orm.Update<TEntity>()
+                .WithTransaction(CurrentUow?.GetOrBeginTransaction())
+                .SetSource(this as TEntity).ExecuteAffrowsAsync() == 1;
+
+        this.Repository.UnitOfWork = CurrentUow;
+        return await this.Repository.UpdateAsync(this as TEntity) == 1;
     }
     /// <summary>
     /// 插入数据
     /// </summary>
-    public virtual void Insert()
+    async public virtual Task Insert()
     {
-        if (this.Repository == null) this.Repository = Orm.GetRepository<TEntity>();
-        this.Repository.Insert(this as TEntity);
+        this.CreateTime = DateTime.Now;
+        if (this.Repository == null)
+            this.Repository = Orm.GetRepository<TEntity>();
+
+        this.Repository.UnitOfWork = CurrentUow;
+        await this.Repository.InsertAsync(this as TEntity);
     }
 
     /// <summary>
     /// 更新或插入
     /// </summary>
     /// <returns></returns>
-    public virtual void Save()
+    async public virtual Task Save()
     {
-        if (this.Repository == null) this.Repository = Orm.GetRepository<TEntity>();
-        this.Repository.InsertOrUpdate(this as TEntity);
+        this.UpdateTime = DateTime.Now;
+        if (this.Repository == null)
+            this.Repository = Orm.GetRepository<TEntity>();
+
+        this.Repository.UnitOfWork = CurrentUow;
+        await this.Repository.InsertOrUpdateAsync(this as TEntity);
     }
 }
 
@@ -125,43 +164,10 @@ public abstract class BaseEntity<TEntity, TKey> : BaseEntity<TEntity> where TEnt
     /// </summary>
     /// <param name="id"></param>
     /// <returns></returns>
-    public static TEntity Find(TKey id)
+    async public static Task<TEntity> Find(TKey id)
     {
-        var item = Select.WhereDynamic(id).First();
+        var item = await Select.WhereDynamic(id).FirstAsync();
         (item as BaseEntity<TEntity>)?.Attach();
         return item;
     }
-}
-
-[Table(DisableSyncStructure = true)]
-public abstract class BaseEntity<TEntity, TKey1, TKey2> : BaseEntity<TEntity> where TEntity : class
-{
-
-    /// <summary>
-    /// 主键1
-    /// </summary>
-    [Column(IsPrimary = true)]
-    public virtual TKey1 PkId1 { get; set; }
-    /// <summary>
-    /// 主键2
-    /// </summary>
-    [Column(IsPrimary = true)]
-    public virtual TKey2 PkId2 { get; set; }
-
-    /// <summary>
-    /// 根据主键值获取数据
-    /// </summary>
-    /// <param name="pkid1">主键1</param>
-    /// <param name="pkid2">主键2</param>
-    /// <returns></returns>
-    public static TEntity Find(TKey1 pkid1, TKey1 pkid2)
-    {
-        var item = Select.WhereDynamic(new
-        {
-            PkId1 = pkid1,
-            PkId2 = pkid2
-        }).First();
-        (item as BaseEntity<TEntity>).Attach();
-        return item;
-    }
 }
\ No newline at end of file
diff --git a/Examples/base_entity/BaseEntityUnitOfWork.cs b/Examples/base_entity/BaseEntityUnitOfWork.cs
new file mode 100644
index 00000000..0199b2c1
--- /dev/null
+++ b/Examples/base_entity/BaseEntityUnitOfWork.cs
@@ -0,0 +1,124 @@
+using FreeSql;
+using SafeObjectPool;
+using System;
+using System.Data;
+using System.Data.Common;
+using System.Threading;
+
+class BaseEntityUnitOfWork : IUnitOfWork
+{
+    internal readonly static AsyncLocal<IUnitOfWork> _asyncUow = new AsyncLocal<IUnitOfWork>();
+
+    protected IFreeSql _fsql;
+    protected Object<DbConnection> _conn;
+    protected DbTransaction _tran;
+
+    public BaseEntityUnitOfWork(IFreeSql fsql)
+    {
+        _fsql = fsql;
+        _asyncUow.Value = this;
+    }
+
+    void ReturnObject()
+    {
+        _fsql.Ado.MasterPool.Return(_conn);
+        _tran = null;
+        _conn = null;
+        _asyncUow.Value = null;
+    }
+
+
+    /// <summary>
+    /// 是否启用工作单元
+    /// </summary>
+    public bool Enable { get; private set; } = true;
+
+    /// <summary>
+    /// 禁用工作单元
+    /// <exception cref="Exception"></exception>
+    /// <para></para>
+    /// 若已开启事务（已有Insert/Update/Delete操作），调用此方法将发生异常，建议在执行逻辑前调用
+    /// </summary>
+    public void Close()
+    {
+        if (_tran != null)
+            throw new Exception("已开启事务，不能禁用工作单元");
+
+        Enable = false;
+    }
+
+    public void Open() =>
+        Enable = true;
+
+    public IsolationLevel? IsolationLevel { get; set; }
+
+    public DbTransaction GetOrBeginTransaction(bool isCreate = true)
+    {
+
+        if (_tran != null) return _tran;
+        if (isCreate == false) return null;
+        if (!Enable) return null;
+        if (_conn != null) _fsql.Ado.MasterPool.Return(_conn);
+
+        _conn = _fsql.Ado.MasterPool.Get();
+        try
+        {
+            _tran = IsolationLevel == null ?
+                _conn.Value.BeginTransaction() :
+                _conn.Value.BeginTransaction(IsolationLevel.Value);
+        }
+        catch
+        {
+            ReturnObject();
+            throw;
+        }
+        return _tran;
+    }
+
+    public void Commit()
+    {
+        if (_tran != null)
+        {
+            try
+            {
+                _tran.Commit();
+            }
+            finally
+            {
+                ReturnObject();
+            }
+        }
+    }
+    public void Rollback()
+    {
+        if (_tran != null)
+        {
+            try
+            {
+                _tran.Rollback();
+            }
+            finally
+            {
+                ReturnObject();
+            }
+        }
+    }
+    ~BaseEntityUnitOfWork()
+    {
+        this.Dispose();
+    }
+    bool _isdisposed = false;
+    public void Dispose()
+    {
+        if (_isdisposed) return;
+        _isdisposed = true;
+        try
+        {
+            this.Rollback();
+        }
+        finally
+        {
+            GC.SuppressFinalize(this);
+        }
+    }
+}
\ No newline at end of file
diff --git a/Examples/base_entity/Entities/User.cs b/Examples/base_entity/Entities/User.cs
index a062d1a0..7db6ab8c 100644
--- a/Examples/base_entity/Entities/User.cs
+++ b/Examples/base_entity/Entities/User.cs
@@ -10,8 +10,6 @@ public class UserGroup : BaseEntity<UserGroup, int>
     public string GroupName { get; set; }
 
     public List<User1> User1s { get; set; }
-
-    public List<User2> User2s { get; set; }
 }
 
 public class Role : BaseEntity<Role, string>
@@ -54,38 +52,3 @@ public class User1 : BaseEntity<User1, Guid>
     /// </summary>
     public string Description { get; set; }
 }
-
-public class User2 : BaseEntity<User2, Guid, int>
-{
-    static User2()
-    {
-        User2.Orm.CodeFirst.ConfigEntity<User2>(t =>
-        {
-            t.Property(a => a.PkId1).Name("UserId");
-            t.Property(a => a.PkId2).Name("Index");
-        });
-    }
-
-    public int GroupId { get; set; }
-    public UserGroup Group { get; set; }
-
-    /// <summary>
-    /// 登陆名
-    /// </summary>
-    public string Username { get; set; }
-
-    /// <summary>
-    /// 昵称
-    /// </summary>
-    public string Nickname { get; set; }
-
-    /// <summary>
-    /// 头像
-    /// </summary>
-    public string Avatar { get; set; }
-
-    /// <summary>
-    /// 描述
-    /// </summary>
-    public string Description { get; set; }
-}
\ No newline at end of file
diff --git a/Examples/base_entity/Program.cs b/Examples/base_entity/Program.cs
index 7de6d4d4..c09610de 100644
--- a/Examples/base_entity/Program.cs
+++ b/Examples/base_entity/Program.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Threading.Tasks;
 
 namespace base_entity
 {
@@ -6,74 +7,70 @@ namespace base_entity
     {
         static void Main(string[] args)
         {
-            var ug1 = new UserGroup();
-            ug1.GroupName = "分组一";
-            ug1.Insert();
+            Task.Run(async () =>
+            {
+                using (var uow = BaseEntity.Begin())
+                {
+                    var itt = await UserGroup.Find(1);
+                }
 
-            var ug2 = new UserGroup();
-            ug2.GroupName = "分组二";
-            ug2.Insert();
+                var ug1 = new UserGroup();
+                ug1.GroupName = "分组一";
+                await ug1.Insert();
 
-            var u1 = new User1();
-            var u2 = new User2();
+                var ug2 = new UserGroup();
+                ug2.GroupName = "分组二";
+                await ug2.Insert();
 
-            u1.GroupId = ug1.Id;
-            u1.Save();
+                var u1 = new User1();
 
-            u2.GroupId = ug2.Id;
-            u2.Save();
+                u1.GroupId = ug1.Id;
+                await u1.Save();
 
-            u1.Delete();
-            u1.Restore();
+                await u1.Delete();
+                await u1.Restore();
 
-            u1.Nickname = "x1";
-            u1.Update();
+                u1.Nickname = "x1";
+                await u1.Update();
 
-            u2.Delete();
-            u2.Restore();
+                var u11 = await User1.Find(u1.Id);
+                u11.Description = "备注";
+                await u11.Save();
 
-            u2.Username = "x2";
-            u2.Update();
+                await u11.Delete();
 
-            var u11 = User1.Find(u1.Id);
-            u11.Description = "备注";
-            u11.Save();
+                var u11null = User1.Find(u1.Id);
 
-            u11.Delete();
+                var u11s = User1.Where(a => a.Group.Id == ug1.Id).Limit(10).ToList();
 
-            var u11null = User1.Find(u1.Id);
+                var u11s2 = User1.Select.LeftJoin<UserGroup>((a, b) => a.GroupId == b.Id).Limit(10).ToList();
 
-            var u11s = User1.Where(a => a.Group.Id == ug1.Id).Limit(10).ToList();
-            var u22s = User2.Where(a => a.Group.Id == ug2.Id).Limit(10).ToList();
+                var ug1s = UserGroup.Select
+                    .IncludeMany(a => a.User1s)
+                    .Limit(10).ToList();
 
-            var u11s2 = User1.Select.LeftJoin<UserGroup>((a, b) => a.GroupId == b.Id).Limit(10).ToList();
-            var u22s2 = User2.Select.LeftJoin<UserGroup>((a, b) => a.GroupId == b.Id).Limit(10).ToList();
+                var ug1s2 = UserGroup.Select.Where(a => a.User1s.AsSelect().Any(b => b.Nickname == "x1")).Limit(10).ToList();
 
-            var ug1s = UserGroup.Select
-                .IncludeMany(a => a.User1s)
-                .IncludeMany(a => a.User2s)
-                .Limit(10).ToList();
+                var r1 = new Role();
+                r1.Id = "管理员";
+                await r1.Save();
 
-            var ug1s2 = UserGroup.Select.Where(a => a.User1s.AsSelect().Any(b => b.Nickname == "x1")).Limit(10).ToList();
+                var r2 = new Role();
+                r2.Id = "超级会员";
+                await r2.Save();
 
-            var r1 = new Role();
-            r1.Id = "管理员";
-            r1.Save();
+                var ru1 = new RoleUser1();
+                ru1.User1Id = u1.Id;
+                ru1.RoleId = r1.Id;
+                await ru1.Save();
 
-            var r2 = new Role();
-            r2.Id = "超级会员";
-            r2.Save();
+                ru1.RoleId = r2.Id;
+                await ru1.Save();
 
-            var ru1 = new RoleUser1();
-            ru1.User1Id = u1.Id;
-            ru1.RoleId = r1.Id;
-            ru1.Save();
+                var u1roles = User1.Select.IncludeMany(a => a.Roles).ToList();
+                var u1roles2 = User1.Select.Where(a => a.Roles.AsSelect().Any(b => b.Id == "xx")).ToList();
 
-            ru1.RoleId = r2.Id;
-            ru1.Save();
-
-            var u1roles = User1.Select.IncludeMany(a => a.Roles).ToList();
-            var u1roles2 = User1.Select.Where(a => a.Roles.AsSelect().Any(b => b.Id == "xx")).ToList();
+            }).Wait();
 
             Console.WriteLine("按任意键结束。。。");
             Console.ReadKey();