Incorrect IsDBNull results on null rowversion when using ReadAsync #1228
Description
When calling IsDBNull on a rowversion column after having called ReadAsync, false is return for a null value instead of true. This occurs on Microsoft.Data.SqlClient 3.0, and is likely related to #998 (/cc @Wraith2).
The below minimal repro uses a left join to produce a null rowversion. This was originally raised and repro'd on EF Core by @frankbuckley in dotnet/efcore#25074, thanks.
Repro
await using var conn = new SqlConnection("Server=localhost;Database=test;User=SA;Password=Abcd5678;Connect Timeout=60;ConnectRetryCount=0");
await conn.OpenAsync();
await using var cmd = new SqlCommand(@"
DROP TABLE IF EXISTS [Price];
DROP TABLE IF EXISTS [Occurrences];
CREATE TABLE [Occurrences] (
[Id] int NOT NULL IDENTITY,
CONSTRAINT [PK_Occurrences] PRIMARY KEY ([Id])
);
CREATE TABLE [Price] (
[Id] int NOT NULL IDENTITY,
[Timestamp] rowversion NOT NULL,
[OccurrenceId] int NOT NULL,
[Value] decimal(18,2) NOT NULL,
CONSTRAINT [PK_Price] PRIMARY KEY ([Id]),
CONSTRAINT [FK_Price_Occurrences_OccurrenceId] FOREIGN KEY ([OccurrenceId]) REFERENCES [Occurrences] ([Id]) ON DELETE CASCADE
);
INSERT INTO [Occurrences] DEFAULT VALUES;
INSERT INTO [Occurrences] DEFAULT VALUES;", conn);
await cmd.ExecuteNonQueryAsync();
cmd.CommandText = @"
SELECT [o].[Id], [p].[Id], [p].[OccurrenceId], [p].[Timestamp], [p].[Value]
FROM [Occurrences] AS [o]
LEFT JOIN [Price] AS [p] ON [o].[Id] = [p].[OccurrenceId]
ORDER BY [o].[Id]";
await using var reader = await cmd.ExecuteReaderAsync();
// Read one row with Read - works fine
reader.Read();
Console.WriteLine($"IsDBNull after Read: {reader.IsDBNull(3)}");
// Read another row with ReadAsync - bug
await reader.ReadAsync();
Console.WriteLine($"IsDBNull after ReadAsync: {reader.IsDBNull(3)}");
_ = reader.GetFieldValue<byte[]>(3); // Throws