Delete Trigger for Memory Optimized Table - in-memory

Question

I am trying to write a Delete Trigger for a Memory Optimized Table in SQL Server 2016 RC 2
CREATE TRIGGER [dbo].[TestCascadeDelete]
ON [CAMSII].[dbo].[Table1]
WITH NATIVE_COMPILATION, SCHEMABINDING
FOR DELETE
AS BEGIN ATOMIC WITH
(
TRANSACTION ISOLATION LEVEL = SNAPSHOT, LANGUAGE = N'us_english'
)
DELETE [dbo].[Table2]
WHERE [dbo].[Table2].Id IN(SELECT Id from DELETED)
END
GO
When I am running this query I am getting following error.
Subqueries (queries nested inside another query) is only supported in SELECT statements with natively compiled modules.

Answer 1

I did a simple trick today for working around this, as I cannot use sub-queries in a natively compiled stored procedure.
Scenario is Delete from Master Child tables:
row exist in parent -> capture id;
while (rowcount <> 0)
begin
delete from child where id = idcaptured;
delete from master where id = idcaptured;
row exist in parent -> capture id;
end;

Answer 2

The workaround is to use a table variable and iterate over the rows with a WHILE loop. Here is an example for an UPDATE with FROM workaround:
DROP TABLE IF EXISTS dbo.table1
GO
DROP TYPE IF EXISTS dbo.type1
GO
CREATE TABLE dbo.table1
(Id INT NOT NULL PRIMARY KEY NONCLUSTERED,
c2 INT NOT NULL,
LastUpdated DATETIME2 NOT NULL DEFAULT (SYSDATETIME()))
WITH (MEMORY_OPTIMIZED=ON)
GO
CREATE TYPE dbo.type1 AS TABLE
(Id INT NOT NULL,
c2 INT NOT NULL,
RowID INT IDENTITY,
INDEX ix_RowID (RowID DESC))
WITH (MEMORY_OPTIMIZED=ON)
GO
CREATE TRIGGER dbo.tr_table1
ON dbo.table1
WITH NATIVE_COMPILATION, SCHEMABINDING
AFTER UPDATE
AS BEGIN ATOMIC WITH
(
TRANSACTION ISOLATION LEVEL = SNAPSHOT, LANGUAGE = N'us_english'
)
-- original UPDATE with FROM statement:
--UPDATE dbo.table1
--SET LastUpdated = SYSDATETIME()
--FROM dbo.table1 t JOIN Inserted i ON t.Id=i.Id
DECLARE #tv dbo.type1
INSERT #tv (Id, c2)
SELECT Id, c2 FROM Inserted
-- workaround that iterates over the rows in the table variable, simulating a cursor:
DECLARE #max INT = SCOPE_IDENTITY()
DECLARE #i INT = 1
DECLARE #Id INT
WHILE #i <= #max
BEGIN
SELECT #Id = Id
FROM #tv
WHERE RowID=#i
UPDATE dbo.table1
SET LastUpdated = SYSDATETIME()
WHERE Id = #Id
SET #i += 1
END
END
GO
INSERT dbo.table1 (Id, c2) VALUES (1,2)
INSERT dbo.table1 (Id, c2) VALUES (2,2)
GO
SELECT * FROM dbo.table1
GO
UPDATE dbo.table1
SET c2 = 3
GO
SELECT * FROM dbo.table1
GO