Replace grouped Id from second table - sql

Question

I have two tables.
Table1
Id, Column1, Column2, Column3
1 1 2 3
2 1 2 3
3 2 1 3
4 2 1 3
5 2 2 2
Table2
Id, Table1_Id
1 1
2 1
3 2
4 2
5 2
6 3
7 4
8 4
9 5
From first table I need remove duplicate rows with same Column1, Column2 and Column3 values and to Table 2 I need replace FKs Table1_Id column with Id after removes duplicate rows from Table1.
I need this
Table1
Id, Column1, Column2, Column3
1 1 2 3
3 2 1 3
5 2 2 2
Table2
Id, Table1_Id
1 1
2 1
3 1
4 1
5 1
6 3
7 3
8 3
9 5

Answer 1

-- Build test data
create table #table1(
id int,
column1 int,
column2 int,
column3 int
)
create table #table2(
id int,
table1_id int
)
insert into #table1
select 1, 1, 2, 3 union all
select 2, 1, 2, 3 union all
select 3, 2, 1, 3 union all
select 4, 2, 1, 3 union all
select 5, 2, 2, 2
insert into #table2
select 1, 1 union all
select 2, 1 union all
select 3, 2 union all
select 4, 2 union all
select 5, 2 union all
select 6, 3 union all
select 7, 4 union all
select 8, 4 union all
select 9, 5
-- update rows of table2
;with cte as(
select
*,
rn = row_number() over(partition by column1, column2, column3 order by id)
from #table1
)
update t2
set t2.table1_id = c.id
from #table2 t2
inner join #table1 t1
on t1.id = t2.table1_id
inner join cte c on
c.column1 = t1.column1
and c.column2 = t1.column2
and c.column3 = t1.column3
and c.rn = 1
-- delete duplicate rows of table1
;with cte as(
select
*,
rn = row_number() over(partition by column1, column2, column3 order by id)
from #table1
)
delete from cte where rn > 1
select * from #table1
select * from #table2
--drop test data
drop table #table1
drop table #table2

Answer 2

-- test tables
declare #t1 table
(Id int, Column1 int, Column2 int, Column3 int)
declare #t2 table
(Id int, Column1 int)
-- data
insert #t1 values
(1,1,2,3),(2,1,2,3),(3,2,1,3),(4,2,1,3),(5,2,2,2)
insert #t2 values (1,1)
,(2,1),(3,2),(4,2),(5,2)
,(6,3),(7,4),(8,4),(9,5)
-- update t2
begin transaction
;with cte as(
select
id,
lowrow_id = min(id) over(partition by column1, column2, column3)
from #t1
)
update t2
set
Column1 = cte.lowrow_id
from
#t2 t2
join cte
on t2.Column1 = cte.id
where cte.lowrow_id < cte.id
-- delete t1
;with cte as(
select
id,
lowrow_id = min(id) over(partition by column1, column2, column3)
from #t1
)
delete cte
where
lowrow_id < id
commit transaction
-- show result
select * from #t1
select * from #t2
Output
Id Column1 Column2 Column3
1 1 2 3
3 2 1 3
5 2 2 2
Id Column1
1 1
2 1
3 1
4 1
5 1
6 3
7 3
8 3
9 5

Answer 3

with tbl1 as (
select ROW_NUMBER() over (partition by column1,column2,column3 order by id) as rownb,min(id) over (partition by column1,column2,column3) as pid,id,column1,column2,column3 from Table1
)
update table2 set Table1_id = tbl1.pid from table2 left join tbl1 on table2.Table1_id = tbl1.id
with tbl1 as (
select ROW_NUMBER() over (partition by column1,column2,column3 order by id) as rownb,min(id) over (partition by column1,column2,column3) as pid,id,column1,column2,column3 from Table1
)
delete from tbl1 where rownb > 1