Tag: delete

-- NOTE: This is an EXAMPLE to show it is possible
-- to achieve moving rows using an implicit transaction
-- from one table into another table.

-- Set up example tables, Foo & Bar.
drop table if exists [dbo].[Bar];
drop table if exists [dbo].[Foo];

create table [dbo].[Bar](
	[ID] [int] identity(1,1) not null primary key clustered,
	[MyKey] [int] null index ix_mykey,
	[MyColumn] [int] null index ix_mycol
)

create table [dbo].[Foo](
	[ID] [int] identity(1,1) not null primary key clustered,
	[MyKey] [int] null index ix_mykey,
	[MyColumn] [int] index ix_mycol,
)
GO

-- Create some dummy data
insert into [dbo].[Foo]( [MyKey], [MyColumn] )
values (1, 11), (2, 22), (3, 33), (4, 44);
GO 10240

-- Verify the rows before.
select count(*) from [dbo].[Foo];
select count(*) from [dbo].[Bar];

-- Move rows from table Foo into table Bar using two styles.

-- Method 1: "Direct" move
delete
from [dbo].[Foo]
output [deleted].[MyKey], [deleted].[MyColumn]
into [dbo].[Bar]( [MyKey], [MyColumn] )
where [ID] % 3 = 1;


-- Method 2: "Subquery" move
insert [dbo].[Bar]( [MyKey], [MyColumn] )
select [MyKey], [MyColumn]
from (
	delete
	from [dbo].[Foo]
	output deleted.*
	where [ID] % 3 = 2
) [MovedRows]
where [MovedRows].[MyKey] = 2;
-- Note: The last where is not needed, just showing it is possible to re-filter incoming [from the deleted output] rows.

-- Verify the counts after.
-- Note: Any deleted rows filtered out via Method 2 are now gone.
select count(*) from [dbo].[Foo];
select count(*) from [dbo].[Bar];