Update with ROW_NUMBER() OVER - sql

Question

I'm getting error "Windowed functions can only appear in the SELECT or ORDER BY clauses." Can you please help me?
Iknow there are already some solutions to this problem but i don't know how to change it for my case. I am a beginner in SQL.
EDIT: I need to update column [BREAG_GUEST_SEQ] with correct sequence at UPDATE case. Every [BREAG_BGL_ID] have own sequence..
UPDATE G1
SET
G1.[BREAG_BGL_ID] = CASE WHEN G1.[BREAG_BGL_ID] <> G2.GROUP_ID THEN G2.GROUP_ID ELSE G1.[BREAG_BGL_ID] END
,G1.[BREAG_GUEST_SEQ] = CASE WHEN G1.[BREAG_BGL_ID] <> G2.GROUP_ID THEN ROW_NUMBER() OVER(ORDER BY G1.[BREAG_BRE_ID] DESC) + (SELECT ISNULL(MAX(BREAG_GUEST_SEQ), 0) FROM BOS_RESADDGUEST
WHERE DATEPART(YEAR, BREAG_DATEFROM) = DATEPART(YEAR, GETDATE()) AND BREAG_BGL_ID = G2.GROUP_ID)
ELSE G1.[BREAG_GUEST_SEQ] END
FROM
BOS_RESADDGUEST G1
INNER JOIN (
SELECT
[BRE_ID]
,MAX([BRE_DATEFROM]) AS DATEFROM
,MAX([BRE_DATETO]) AS DATETO
,MAX(BGL_ID) AS GROUP_ID
FROM
BOS_RESERVATION
LEFT JOIN BOS_UNIT_LIST ON BUL_ID = BRE_UNIT_ID
LEFT JOIN BOS_UNITTYPE_LIST ON BUL_UNITTYPE_ID = BUT_ID
LEFT JOIN BOS_GROUP_LIST ON BGL_ID = BUT_GROUP_ID
WHERE
BRE_ID = #DIALOG_BRE_ID
GROUP BY [BRE_ID]
) AS G2
ON G2.[BRE_ID] = G1.[BREAG_BRE_ID]

Answer 1

This isnt tested nor do you provide expected results or data structure. However, the issue is quite clear (as SMor has pointed out in the comments). This isnt the best code and the indentation is awful (i want it to be readable with scrolling left or right here on SO).
You most likely have to edit what Im joining on in the update statement at the end, because without further information from you i have to guess what the join predicate ought to be. Im sure you can figure it out from this point forward.
; WITH cte AS
(
SELECT
[BREAG_BRE_ID]
, CASE
WHEN x.[BREAG_BGL_ID] <> x.GROUP_ID THEN x.GROUP_ID
ELSE x.[BREAG_BGL_ID]
END As NewBREAGBGLID
, CASE
WHEN x.[BREAG_BGL_ID] <> x.GROUP_ID THEN ROW_NUMBER()
OVER (ORDER BY x.[BREAG_BRE_ID] DESC) +
(
SELECT ISNULL(MAX(BREAG_GUEST_SEQ), 0)
FROM BOS_RESADDGUEST
WHERE DATEPART(YEAR, BREAG_DATEFROM) = DATEPART(YEAR, GETDATE())
AND BREAG_BGL_ID = x.GROUP_ID
)
ELSE x.[BREAG_GUEST_SEQ]
END AS NewBREAGGUESTSEQ
FROM
(
SELECT g2.*, g1.[BREAG_BGL_ID], g1.[BREAG_BRE_ID], g1.[BREAG_GUEST_SEQ]
FROM
BOS_RESADDGUEST G1
INNER JOIN
(
SELECT
[BRE_ID]
,MAX([BRE_DATEFROM]) AS DATEFROM
,MAX([BRE_DATETO]) AS DATETO
,MAX(BGL_ID) AS GROUP_ID
FROM
BOS_RESERVATION
LEFT JOIN BOS_UNIT_LIST ON BUL_ID = BRE_UNIT_ID
LEFT JOIN BOS_UNITTYPE_LIST ON BUL_UNITTYPE_ID = BUT_ID
LEFT JOIN BOS_GROUP_LIST ON BGL_ID = BUT_GROUP_ID
WHERE
BRE_ID = #DIALOG_BRE_ID
GROUP BY [BRE_ID]
) AS G2
ON G2.[BRE_ID] = G1.[BREAG_BRE_ID]
) AS x
)
UPDATE
[BREAG_BGL_ID] = c.NewBREAGBGLID
, [BREAG_GUEST_SEQ] = c.NewBREAGGUESTSEQ
FROM BOS_RESADDGUEST br
INNER JOIN cte c ON br.[BREAG_BRE_ID] =c.[BREAG_BRE_ID]

Answer 2

You need to move the ROW_NUMBER into a derived table or CTE. You can update this directly, no need to rejoin.
You can also change the subquery to a windowed MAX
Note also that date comparisons should not use functions against the column, as this can affect performance
UPDATE G1
SET
G1.[BREAG_BGL_ID] = CASE WHEN G1.[BREAG_BGL_ID] <> G2.GROUP_ID THEN G2.GROUP_ID ELSE G1.[BREAG_BGL_ID] END
,G1.[BREAG_GUEST_SEQ] = CASE WHEN G1.[BREAG_BGL_ID] <> G2.GROUP_ID THEN G1.rn + G1.MaxSeq ELSE G1.[BREAG_GUEST_SEQ] END
FROM (
SELECT *,
ROW_NUMBER() OVER(ORDER BY G1.[BREAG_BRE_ID] DESC) AS rn,
ISNULL(MAX(CASE WHEN WHERE G1.BREAG_DATEFROM >= DATEFROMPARTS(YEAR(GETDATE()), 1, 1) THEN G1.BREAG_GUEST_SEQ END)
OVER (PARTITION BY G1.BREAG_BGL_ID), 0) AS MaxSeq
FROM
BOS_RESADDGUEST G1
) AS G1
INNER JOIN (
SELECT
[BRE_ID]
,MAX([BRE_DATEFROM]) AS DATEFROM
,MAX([BRE_DATETO]) AS DATETO
,MAX(BGL_ID) AS GROUP_ID
FROM
BOS_RESERVATION
LEFT JOIN BOS_UNIT_LIST ON BUL_ID = BRE_UNIT_ID
LEFT JOIN BOS_UNITTYPE_LIST ON BUL_UNITTYPE_ID = BUT_ID
LEFT JOIN BOS_GROUP_LIST ON BGL_ID = BUT_GROUP_ID
WHERE
BRE_ID = #DIALOG_BRE_ID
GROUP BY [BRE_ID]
) AS G2
ON G2.[BRE_ID] = G1.[BREAG_BRE_ID];