如何在更新和插入并发时避免重复行

Question

我有这个代码：

public class MyService : IMyService
{
    public EarningService(IDbConnection db)
    {
        Db = db;
    }

    public async Task SomeMethodWithTransacion()
    {
        Db.Open();
        var tran = Db.BeginTransaction();

        try
        {
            string sqlInsert1 = "insert into someTable1";
            await Db.ExecuteAsync(sqlInsert1, new {param1});
    
            string sqlInsert2 = "insert into someTable2";
            await Db.ExecuteAsync(sqlInsert2, new {param2})
    
            var field1 = GetSomeField1(param);
       
            string updateQuery1 = @"UPDATE SOMETABLE1 SET someField = 'someValue' WHERE Id = @Id";
            Db.Execute(updateQuery1, new { Id });
    
            string sqlInsert3 = "insert into someTable3";
            await Db.ExecuteAsync(sqlInsert3, new {param3});
    
            var field2 = GetField2(param);
            var field3 = GetField3(param);
            var field4 = GetField4(param);
        
            string sqlInsert4 = "insert into someTable4";
            await Db.ExecuteAsync(sqlInsert4, new {param4});

            var sqlSP = "[AddAssets]";
            await Db.ExecuteAsync(sqlSP, new { @owner= @owner, @rvalue = value }, tran,
                   commandType: CommandType.StoredProcedure);

            tran.Commit();
            return;
        }
        catch (Exception e)
        {
            tran.Rollback();
            return 500;
        }
   }
}

//startup
public void ConfigureServices(IServiceCollection services)
{
    string dbConnectionString = this.Configuration.GetConnectionString("Default");

    // Inject IDbConnection, with implementation from SqlConnection class.
    services.AddTransient<IDbConnection>((sp) => new SqlConnection(dbConnectionString));  
}      

但是我在执行下面的代码时遇到了问题：

var sqlSP = "[AddAssets]";
                await Db.ExecuteAsync(sqlSP, new { @owner= @owner, @rvalue = value }, tran,
                       commandType: CommandType.StoredProcedure);

存储过程：

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

ALTER PROCEDURE [dbo].[AddAssets] 
    @owner uniqueidentifier, 
    @rvalue nvarchar(MAX)
AS
BEGIN
    DECLARE @currentBal decimal = (SELECT TOP (1) [Balance] 
                                   FROM [dbo].[Assets] 
                                   WHERE [Owner] = @owner AND [Status]=1)

    IF @currentBal >= 0
    BEGIN
        DECLARE @assetTable TABLE
                            (
                                [Id] [int] NOT NULL,
                                [Owner] [uniqueidentifier] NULL,
                                [Balance] [decimal](18, 2) NULL,
                                [Status] [smallint] NULL
                            );

    INSERT INTO @assetTable 
        SELECT TOP 1 
            [Id], [Owner], [Balance], [Status] 
        FROM [dbo].[Assets] WITH (UPDLOCK) 
        WHERE [Owner] = @owner AND [Status] = 1;

    INSERT INTO [dbo].[Assets] ([Owner], [Balance], [Status])
    VALUES (@owner, @rvalue, 1)

    UPDATE [dbo].[Assets] 
    SET [Status] = 2  
    WHERE [Id] = (SELECT TOP 1 [Id] FROM @assetTable 
                  WHERE [Owner] = @owner);
END

我确实使用 jmeter 对该方法进行了负载测试，但得到了以下预期结果：

Id	Owner	Balance	Status	RV
2	3B09C822-E613-454B-A6AA-53FA68363F74	102.00	1	0x000000000007186D
12	3B09C822-E613-454B-A6AA-53FA68363F74	103.00	1	0x000000000007186F
13	3B09C822-E613-454B-A6AA-53FA68363F74	103.00	1	0x0000000000071871
14	3B09C822-E613-454B-A6AA-53FA68363F74	103.00	1	0x0000000000071873
15	3B09C822-E613-454B-A6AA-53FA68363F74	103.00	1	0x0000000000071875
16	3B09C822-E613-454B-A6AA-53FA68363F74	61.00	1	0x0000000000071877
17	3B09C822-E613-454B-A6AA-53FA68363F74	86.00	1	0x0000000000071879
18	3B09C822-E613-454B-A6AA-53FA68363F74	88.00	1	0x000000000007187B
19	3B09C822-E613-454B-A6AA-53FA68363F74	77.00	1	0x000000000007187D
20	3B09C822-E613-454B-A6AA-53FA68363F74	51.00	1	0x000000000007187F

当我预期结果是只有 1 行的状态 = 1 对于 1 个所有者：

Id	Owner	Balance	Status	RV
2	3B09C822-E613-454B-A6AA-53FA68363F74	102.00	1	0x000000000007186D
12	3B09C822-E613-454B-A6AA-53FA68363F74	103.00	2	0x000000000007186F
13	3B09C822-E613-454B-A6AA-53FA68363F74	103.00	2	0x0000000000071871
14	3B09C822-E613-454B-A6AA-53FA68363F74	103.00	2	0x0000000000071873
15	3B09C822-E613-454B-A6AA-53FA68363F74	103.00	2	0x0000000000071875
16	3B09C822-E613-454B-A6AA-53FA68363F74	61.00	2	0x0000000000071877
17	3B09C822-E613-454B-A6AA-53FA68363F74	86.00	2	0x0000000000071879
18	3B09C822-E613-454B-A6AA-53FA68363F74	88.00	2	0x000000000007187B
19	3B09C822-E613-454B-A6AA-53FA68363F74	77.00	2	0x000000000007187D
20	3B09C822-E613-454B-A6AA-53FA68363F74	51.00	2	0x000000000007187F

请有人帮我解决这个问题。

Answer 1

您的代码很复杂，我尝试在另一个更简单的代码中编写相同的逻辑，并且我添加了 WITH (rowlock,UpdLock) 代码来读取更新的值并锁定行直到事务结束：

试试这个：

ALTER PROCEDURE [AddAssets] 
(
    @owner      uniqueidentifier, 
    @rvalue     nvarchar(MAX)
)
AS
BEGIN
    declare @valid_balance_id as int;
    
    -- select last added
    set @valid_balance_id = (
        SELECT      TOP (1) 
                    [Id] 
        FROM        [Assets] WITH (rowlock,UpdLock) 
        WHERE       [Owner] = @owner  
                AND 
                    [Status] = 1 
        ORDER BY    [Id] DESC
    );

    -- if no value exit
    if @valid_balance_id is null 
    BEGIN
        return -1;
    END

    -- if selected id has balance >= 0
    set @valid_balance_id = (
        SELECT      TOP (1) 
                    [Id] 
        FROM        [Assets] WITH (rowlock,UpdLock) 
        WHERE       [Balance] >= 0 
                AND 
                    [Id] = @valid_balance_id 
    );

    -- if row has no balance or negative balance then exit
    if @valid_balance_id is null 
    BEGIN
        return -1;
    END

    -- set status = 2 for the valid value
    update  TOP (1)
            [Assets] 
    SET     [Status] = 2 
    WHERE   [Id] = @valid_balance_id;

    -- insert new value
    INSERT INTO [Assets]
    (
        [Owner], [Balance], [Status]
    )
    VALUES
    (
        @owner, @rvalue, 1
    );
END