diff --git a/XCode/DataAccessLayer/Common/DbBase.cs b/XCode/DataAccessLayer/Common/DbBase.cs
index 92370bd56..fcf3d076e 100644
--- a/XCode/DataAccessLayer/Common/DbBase.cs
+++ b/XCode/DataAccessLayer/Common/DbBase.cs
@@ -957,7 +957,7 @@ public virtual IDataParameter CreateParameter(String name, Object? value, Type?
     /// <summary>创建参数数组</summary>
     /// <param name="ps"></param>
     /// <returns></returns>
-    public virtual IDataParameter[] CreateParameters(IDictionary<String, Object> ps) => ps.Select(e => CreateParameter(e.Key, e.Value)).ToArray();
+    public virtual IDataParameter[] CreateParameters(IDictionary<String, Object>? ps) => ps?.Select(e => CreateParameter(e.Key, e.Value)).ToArray() ?? new IDataParameter[0];
 
     /// <summary>根据对象成员创建参数数组</summary>
     /// <param name="model"></param>
diff --git a/XCode/DataAccessLayer/DAL_DbOperate.cs b/XCode/DataAccessLayer/DAL_DbOperate.cs
index 83aa945a0..de297d4c6 100644
--- a/XCode/DataAccessLayer/DAL_DbOperate.cs
+++ b/XCode/DataAccessLayer/DAL_DbOperate.cs
@@ -1,10 +1,6 @@
-using System;
-using System.Collections.Generic;
-using System.Data;
+using System.Data;
 using System.Text;
 using System.Text.RegularExpressions;
-using System.Threading;
-using System.Threading.Tasks;
 using NewLife;
 using NewLife.Caching;
 using NewLife.Collections;
@@ -177,7 +173,7 @@ public Int32 Execute(String sql, CommandType type, IDictionary<String, Object> p
 
     /// <summary>执行SQL语句，返回受影响的行数</summary>
     /// <param name="sql">SQL语句</param>
-    /// <param name="commandTimeout">命令超时时间，一般用于需要长时间执行的命令</param>
+    /// <param name="commandTimeout">命令超时时间，一般用于需要长时间执行的命令。单位秒</param>
     /// <returns></returns>
     public Int32 Execute(String sql, Int32 commandTimeout)
     {
diff --git a/XUnitTest.XCode/DataAccessLayer/DAL_DbOperate_Tests.cs b/XUnitTest.XCode/DataAccessLayer/DAL_DbOperate_Tests.cs
new file mode 100644
index 000000000..2892a3ed1
--- /dev/null
+++ b/XUnitTest.XCode/DataAccessLayer/DAL_DbOperate_Tests.cs
@@ -0,0 +1,294 @@
+using System;
+using System.Collections.Generic;
+using System.Data;
+using System.Linq;
+using NewLife.Data;
+using NewLife.Security;
+using XCode;
+using XCode.DataAccessLayer;
+using XCode.Membership;
+using Xunit;
+
+namespace XUnitTest.XCode.DataAccessLayer;
+
+public class DAL_DbOperate_Tests
+{
+    public DAL_DbOperate_Tests()
+    {
+        EntityFactory.InitEntity(typeof(User));
+    }
+
+    [Fact]
+    public void PageSplit()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var sql = "select * from user where name=@name order by id";
+        var sb = new SelectBuilder(sql);
+        var rs = dal.PageSplit(sb, 5, 7);
+        Assert.NotNull(rs);
+
+        var sql2 = rs.ToString();
+        Assert.Equal("Select * From user Where name=@name Order By id limit 5, 7", sql2);
+
+        rs = dal.PageSplit(sb, 0, 7);
+        sql2 = rs.ToString();
+        Assert.Equal("Select * From user Where name=@name Order By id limit 7", sql2);
+
+        rs = dal.PageSplit(sb, -1, 7);
+        sql2 = rs.ToString();
+        Assert.Equal("Select * From user Where name=@name Order By id limit 7", sql2);
+
+        Assert.ThrowsAny<NotSupportedException>(() => rs = dal.PageSplit(sb, 1, -7));
+
+        rs = dal.PageSplit(sb, -1, -7);
+        sql2 = rs.ToString();
+        Assert.Equal("Select * From user Where name=@name Order By id", sql2);
+    }
+
+    [Fact]
+    public void Select()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var ds = dal.Select("select * from user");
+        Assert.NotNull(ds);
+        Assert.True(ds.Tables[0].Rows.Count > 0);
+
+        var sb = new SelectBuilder("select * from user");
+        ds = dal.Select(sb, 55, 7);
+        Assert.NotNull(ds);
+        Assert.True(ds.Tables[0].Rows.Count == 0);
+
+        var p = dal.Db.CreateParameter("name", "admin");
+        ds = dal.Select("select * from user where name=@name", CommandType.Text, p);
+        Assert.NotNull(ds);
+        Assert.True(ds.Tables[0].Rows.Count == 1);
+
+        ds = dal.Select("select * from user where name=@name", CommandType.Text, new { name = "admin" }.ToDictionary());
+        Assert.NotNull(ds);
+        Assert.True(ds.Tables[0].Rows.Count == 1);
+    }
+
+    [Fact]
+    public void SelectCount()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var count = dal.SelectCount("select * from user", CommandType.Text);
+        Assert.True(count > 0);
+
+        var p = dal.Db.CreateParameter("name", "admin");
+        count = dal.SelectCount("select * from user where name=@name", CommandType.Text, p);
+        Assert.True(count > 0);
+
+        var sb = new SelectBuilder("select * from user");
+        count = dal.SelectCount(sb);
+        Assert.True(count > 0);
+    }
+
+    [Fact]
+    public void Query()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var dt = dal.Query("select * from user");
+        Assert.NotNull(dt);
+        Assert.True(dt.Rows.Count > 0);
+
+        dt = dal.Query("select * from user where name=@name", new { name = "admin" }.ToDictionary());
+        Assert.NotNull(dt);
+        Assert.Single(dt.Rows);
+
+        dt = dal.Query("select * from user where name=@name1234", new { name1234 = "admin" }.ToDictionary());
+        Assert.NotNull(dt);
+        Assert.Single(dt.Rows);
+
+        var sb = new SelectBuilder("select * from user");
+        dt = dal.Query(sb, 55, 7);
+        Assert.NotNull(dt);
+        Assert.True(dt.Rows.Count == 0);
+    }
+
+    [Fact]
+    public void Execute()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var id = dal.InsertAndGetIdentity($"insert into user(name) values('{Rand.NextString(8)}')");
+        Assert.True(id > 0);
+
+        var rs = dal.Execute("update user set enable=1 where id=" + id);
+        Assert.True(rs > 0);
+
+        rs = dal.Execute("delete from user where id=" + id);
+        Assert.True(rs > 0);
+    }
+
+    [Fact]
+    public void ExecuteWithParameter()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var p = dal.Db.CreateParameter("name", Rand.NextString(8));
+        var id = dal.InsertAndGetIdentity("insert into user(name) values(@name)", CommandType.Text, p);
+        Assert.True(id > 0);
+
+        var ps = dal.Db.CreateParameter("id", id);
+        var rs = dal.Execute("update user set enable=1 where id=@id", CommandType.Text, ps);
+        Assert.True(rs > 0);
+
+        rs = dal.Execute("update user set code=@code where id=@id", CommandType.Text, new { id, code = Rand.NextString(8) }.ToDictionary());
+        Assert.True(rs > 0);
+
+        rs = dal.Execute("delete from user where id=@id", CommandType.Text, ps);
+        Assert.True(rs > 0);
+    }
+
+    [Fact]
+    public void ExecuteWithTimeout()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var rs = dal.Execute("delete from user where id>=10", 15);
+        Assert.True(rs >= 0);
+
+        rs = dal.Execute("delete from user where id>=10", 0);
+        Assert.True(rs >= 0);
+    }
+
+    [Fact]
+    public void ExecuteScalar()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var id = dal.ExecuteScalar<Int64>("select id from user where name=@name", CommandType.Text, new { name = "admin" }.ToDictionary());
+        Assert.True(id > 0);
+
+        id = dal.ExecuteScalar<Int64>("select id from user", CommandType.Text, null);
+        Assert.True(id > 0);
+    }
+
+    //[Fact]
+    //public async void SelectAsync()
+    //{
+    //    var dal = User.Meta.Session.Dal;
+
+    //    var ds = await dal.SelectAsync("select * from user");
+    //    Assert.NotNull(ds);
+    //    Assert.True(ds.Tables[0].Rows.Count > 0);
+
+    //    var sb = new SelectBuilder("select * from user");
+    //    ds = await dal.SelectAsync(sb, 55, 7);
+    //    Assert.NotNull(ds);
+    //    Assert.True(ds.Tables[0].Rows.Count == 0);
+
+    //    var p = dal.Db.CreateParameter("name", "admin");
+    //    ds = await dal.SelectAsync("select * from user where name=@name", CommandType.Text, p);
+    //    Assert.NotNull(ds);
+    //    Assert.True(ds.Tables[0].Rows.Count == 1);
+
+    //    ds = await dal.SelectAsync("select * from user where name=@name", CommandType.Text, new { name = "admin" }.ToDictionary());
+    //    Assert.NotNull(ds);
+    //    Assert.True(ds.Tables[0].Rows.Count == 1);
+    //}
+
+    [Fact]
+    public async void SelectCountAsync()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var count = await dal.SelectCountAsync("select * from user", CommandType.Text);
+        Assert.True(count > 0);
+
+        var p = dal.Db.CreateParameter("name", "admin");
+        count = await dal.SelectCountAsync("select * from user where name=@name", CommandType.Text, p);
+        Assert.True(count > 0);
+
+        var sb = new SelectBuilder("select * from user");
+        count = await dal.SelectCountAsync(sb);
+        Assert.True(count > 0);
+    }
+
+    [Fact]
+    public async void QueryAsync()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var dt = await dal.QueryAsync("select * from user");
+        Assert.NotNull(dt);
+        Assert.True(dt.Rows.Count > 0);
+
+        dt = await dal.QueryAsync("select * from user where name=@name", new { name = "admin" }.ToDictionary());
+        Assert.NotNull(dt);
+        Assert.Single(dt.Rows);
+
+        dt = await dal.QueryAsync("select * from user where name=@name1234", new { name1234 = "admin" }.ToDictionary());
+        Assert.NotNull(dt);
+        Assert.Single(dt.Rows);
+
+        var sb = new SelectBuilder("select * from user");
+        dt = await dal.QueryAsync(sb, 55, 7);
+        Assert.NotNull(dt);
+        Assert.True(dt.Rows.Count == 0);
+    }
+
+    [Fact]
+    public async void ExecuteAsync()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var id = await dal.InsertAndGetIdentityAsync($"insert into user(name) values('{Rand.NextString(8)}')");
+        Assert.True(id > 0);
+
+        var rs = await dal.ExecuteAsync("update user set enable=1 where id=" + id);
+        Assert.True(rs > 0);
+
+        rs = await dal.ExecuteAsync("delete from user where id=" + id);
+        Assert.True(rs > 0);
+    }
+
+    [Fact]
+    public async void ExecuteAsyncWithParameter()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var p = dal.Db.CreateParameter("name", Rand.NextString(8));
+        var id = await dal.InsertAndGetIdentityAsync("insert into user(name) values(@name)", CommandType.Text, p);
+        Assert.True(id > 0);
+
+        var ps = dal.Db.CreateParameter("id", id);
+        var rs = await dal.ExecuteAsync("update user set enable=1 where id=@id", CommandType.Text, ps);
+        Assert.True(rs > 0);
+
+        rs = await dal.ExecuteAsync("update user set code=@code where id=@id", CommandType.Text, new { id, code = Rand.NextString(8) }.ToDictionary());
+        Assert.True(rs > 0);
+
+        rs = await dal.ExecuteAsync("delete from user where id=@id", CommandType.Text, ps);
+        Assert.True(rs > 0);
+    }
+
+    [Fact]
+    public async void ExecuteAsyncWithTimeout()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var rs = await dal.ExecuteAsync("delete from user where id>=10", 15);
+        Assert.True(rs >= 0);
+
+        rs = await dal.ExecuteAsync("delete from user where id>=10", 0);
+        Assert.True(rs >= 0);
+    }
+
+    [Fact]
+    public async void ExecuteScalarAsync()
+    {
+        var dal = User.Meta.Session.Dal;
+
+        var id = await dal.ExecuteScalarAsync<Int64>("select id from user where name=@name", CommandType.Text, new { name = "admin" }.ToDictionary());
+        Assert.True(id > 0);
+
+        id = await dal.ExecuteScalarAsync<Int64>("select id from user", CommandType.Text, null);
+        Assert.True(id > 0);
+    }
+}
\ No newline at end of file
diff --git a/XUnitTest.XCode/DataAccessLayer/DAL_Mapper_Tests.cs b/XUnitTest.XCode/DataAccessLayer/DAL_Mapper_Tests.cs
index fba53ff51..eda117230 100644
--- a/XUnitTest.XCode/DataAccessLayer/DAL_Mapper_Tests.cs
+++ b/XUnitTest.XCode/DataAccessLayer/DAL_Mapper_Tests.cs
@@ -26,6 +26,9 @@ public void Query()
         var list = dal.Query<MyUser>("select * from user", null, 0, 100).ToList();
         Assert.True(list.Count > 0);
 
+        list = dal.Query<MyUser>("select * from user").ToList();
+        Assert.NotNull(list);
+
         list = dal.Query<MyUser>("select * from user where name=@name", new { Name = "admin" }).ToList();
         Assert.NotNull(list);
         Assert.Single(list);