Update several columns with latest values from another table - sql-server

Question

Here's the data:
[ TABLE_1 ]
id | prod1 | date1 | prod2 | date2 | prod3 | date3 |
---|--------|--------|--------|--------|--------|-------|
1 | null | null | null | null | null | null |
2 | null | null | null | null | null | null |
3 | null | null | null | null | null | null |
[ TABLE_2 ]
id | date | product |
-----|-------------|-----------|
1 | 20140101 | X |
1 | 20140102 | Y |
1 | 20140103 | Z |
2 | 20141201 | data |
2 | 20141201 | Y |
2 | 20141201 | Z |
3 | 20150101 | data2 |
3 | 20150101 | data3 |
3 | 20160101 | X |
Both tables have other columns not listed here.
date is formatted: yyyymmdd and datatype is int.
[ TABLE_2 ] doesn't have empty rows, just tried to make sample above more readable.
Here's the Goal:
I need to update [ TABLE_1 ] prod1,date1,prod2,date2,prod3,date3
with product collected from [ TABLE_2 ] with corresponding date values.
Data must be sorted so that "latest" product becomes prod1,
2nd latest product will be prod2 and 3rd is prod3.
Latest product = biggest date (int).
If dates are equal, order doesn't matter. (see id=2 and id=3).
Updated [ TABLE_1 ] should be:
id | prod1 | date1 | prod2 | date2 | prod3 | date3 |
---|--------|----------|--------|----------|--------|----------|
1 | Z | 20140103 | Y | 20140102 | X | 20140101 |
2 | data | 20141201 | Y | 20141201 | Z | 20141201 |
3 | X | 20160101 | data2 | 20150101 | data3 | 20150101 |
Ultimate goal is to get the following :
[ TABLE_3 ]
id | order1 | order2 | order3 | + Columns from [ TABLE_1 ]
---|--------------------|----------------------|------------|--------------------------
1 | 20140103:Z | 20140102:Y | 20140103:Z |
2 | 20141201:data:Y:Z | NULL | NULL |
3 | 20160101:X | 20150101:data2:data3 | NULL |
I have to admit this exceeds my knowledge and I haven't tried anything.
Should I do it with JOIN or SELECT subquery?
Should I try to make it in one SQL -clause or perhaps in 3 steps,
each prod&date -pair at the time ?
What about creating [ TABLE_3 ] ?
It has to have columns from [ TABLE_1 ].
Is it easiest to create it from [ TABLE_2 ] -data or Updated [ TABLE_1 ] ?
Any help would be highly appreciated.
Thanks in advance.
I'll post some of my own shots on comments.

Answer 1

After looking into it (after my comment), a stored procedure would be best, that you can call to view the data as a pivot, and do away with TABLE_1. Obviously if you need to make this dynamic, you'll need to look into dynamic pivots, it's a bit of a hack with CTEs:
CREATE PROCEDURE DBO.VIEW_AS_PIVOTED_DATA
AS
;WITH CTE AS (
SELECT ID, [DATE], 'DATE' + CAST(ROW_NUMBER() OVER(PARTITION BY ID ORDER BY [DATE] DESC) AS VARCHAR) AS [RN]
FROM TABLE_2)
, CTE2 AS (
SELECT ID, PRODUCT, 'PROD' + CAST(ROW_NUMBER() OVER(PARTITION BY ID ORDER BY [DATE] DESC) AS VARCHAR) AS [RN]
FROM TABLE_2)
, CTE3 AS (
SELECT ID, [DATE1], [DATE2], [DATE3]
FROM CTE
PIVOT(MAX([DATE]) FOR RN IN ([DATE1],[DATE2],[DATE3])) PIV)
, CTE4 AS (
SELECT ID, [PROD1], [PROD2], [PROD3]
FROM CTE2
PIVOT(MAX(PRODUCT) FOR RN IN ([PROD1],[PROD2],[PROD3])) PIV)
SELECT A.ID, [PROD1], [DATE1], [PROD2], [DATE2], [PROD3], [DATE3]
FROM CTE3 AS A
JOIN CTE4 AS B
ON A.ID=B.ID

Answer 2

Construction:
WITH ranked AS (
SELECT [id]
,[date]
,[product]
,row_number() over (partition by id order by date desc) rn
FROM [sistemy].[dbo].[TABLE_2]
)
SELECT id, [prod1],[date1],[prod2],[date2],[prod3],[date3]
FROM
(
SELECT id, type+cast(rn as varchar(1)) col, value
FROM ranked
CROSS APPLY
(
SELECT 'date', CAST([date] AS varchar(8))
UNION ALL
SELECT 'prod', product
) ca(type, value)
) unpivoted
PIVOT
(
max(value)
for col IN ([prod1],[date1],[prod2],[date2],[prod3],[date3])
) pivoted
You need to take a few steps to achive the aim.
Rank your products by date:
SELECT [id]
,[date]
,[product]
,row_number() over (partition by id order by date desc) rn
FROM [sistemy].[dbo].[TABLE_2]
Unpivot your date and product columns into one column. You can use UNPIVOT OR CROSS APPLY statements. I prefer CROSS APPLY
SELECT id, type+cast(rn as varchar(1)) col, value
FROM ranked
CROSS APPLY
(
SELECT 'date', CAST([date] AS varchar(8))
UNION ALL
SELECT 'prod', product
) ca(type, value)
or the same result using UNPIVOT
SELECT id, type+cast(rn as varchar(1)) col, value
FROM (
SELECT [id],
rn,
CAST([date] AS varchar(500)) date,
CAST([product] AS varchar(500)) prod
FROM ranked) t
UNPIVOT
(
value FOR type IN (date, product)
) unpvt
and at last you use PIVOTE and get a result.