How to get columns names that been updated - sql

Question

Suppose I have a table like this :
Table 1:
date account name type status open_account_date
31.12.14 1000 20 40 50 31.12.14
2.1.15 1000 10 10 50 31.12.14
3.1.15 1000 5 15 50 31.12.14
and I want to build a summary table like this for the first quarter :
account numOfChanges Changes
1000 4 (name, type)
The first row in table 1 indicats that that the account was opened and somebody enterd for the account some details but the others indicats changes but i want to know which fields has been changed. Is there any suggestion or an idea how to perform this?

Answer 1

DECLARE #StartOfQuarter DATE = '1/1/2015'
;WITH cteRcordStateBeforeQuarter AS (
SELECT
[date]
,account
,name
,[type]
,[status]
,open_account_date
,RowNum = ROW_NUMBER() OVER (PARTITION BY account ORDER BY [date] DESC)
FROM
#Table
WHERE
[date] < #StartOfQuarter
)
, cteRecordStatesDuringQuarter AS (
SELECT
[date]
,account
,name
,[type]
,[status]
,open_account_date
,RowNum = ROW_NUMBER() OVER (PARTITION BY account ORDER BY [date] ASC) + 1
--add 1 because the first row is going to be the last one prior to quarter
,LatestChangeRowNum = ROW_NUMBER() OVER (PARTITION BY account ORDER BY [date] DESC)
FROM
#Table
WHERE
DATEPART(QQ,[date]) = 1
--change to suite ongoing needs such as quater and YEAR([date]) = ??
)
, cteRecursive AS (
SELECT
[date]
,account
,name
,[type]
,[status]
,open_account_date
,RowNum
,LatestChangeRowNum = 0
,NumOfChanges = 0
,[Changes] = CAST('' AS VARCHAR(100))
FROM
cteRcordStateBeforeQuarter
WHERE
RowNum = 1
UNION ALL
SELECT
q.[date]
,q.account
,q.name
,q.[type]
,q.[status]
,q.open_account_date
,q.RowNum
,LatestChangeRowNum = CAST(q.LatestChangeRowNum AS INT)
,NumOfChanges = r.NumOfChanges
+ CASE WHEN ISNULL(q.name,-99999) <> ISNULL(r.name,-99999) THEN 1 ELSE 0 END
+ CASE WHEN ISNULL(q.[type],-99999) <> ISNULL(r.[type],-99999) THEN 1 ELSE 0 END
+ CASE WHEN ISNULL(q.[status],-99999) <> ISNULL(r.[status],-99999) THEN 1 ELSE 0 END
+ CASE WHEN ISNULL(q.open_account_date,'1/1/1900') <> ISNULL(r.open_account_date,'1/1/1900') THEN 1 ELSE 0 END
,[Changes] = CAST(ISNULL(r.[Changes],'')
+ CASE WHEN ISNULL(q.name,-99999) <> ISNULL(r.name,-99999) AND r.[Changes] NOT LIKE '%name%' THEN ',name' ELSE '' END
+ CASE WHEN ISNULL(q.[type],-99999) <> ISNULL(r.[type],-99999) AND r.[Changes] NOT LIKE '%type%' THEN ',type' ELSE '' END
+ CASE WHEN ISNULL(q.[status],-99999) <> ISNULL(r.[status],-99999) AND r.[Changes] NOT LIKE '%status%' THEN ',status' ELSE '' END
+ CASE WHEN ISNULL(q.open_account_date,'1/1/1900') <> ISNULL(r.open_account_date,'1/1/1900') AND r.[Changes] NOT LIKE '%open_account_date%' THEN ',open_account_date' ELSE '' END
AS VARCHAR(100))
FROM
cteRecordStatesDuringQuarter q
INNER JOIN cteRecursive r
ON q.account = r.account
AND q.RowNum = r.RowNum + 1
)
SELECT
account
,NumOfChanges
,[Changes] = REPLACE(IIF(CHARINDEX(',',[Changes]) = 1, RIGHT([Changes],LEN([Changes]) - 1),[Changes]),',',', ')
FROM
cteRecursive
WHERE
LatestChangeRowNum = 1
If you where using SQL 2012 + it would be a little easier because you could use LAG or LEAD window functions and IIF instead of case. But a recursive cte works pretty well too. I assume your recordset will have multiple accounts as well as multiple quarters and there for multiple recordstates prior to the quarter. Due to this you will need to tweak the date logic slightly but this will give you the gist.
First find the record state prior to the quarter. Then find all of the changes during the quarter. Add some row numbers to determine which is the first and which is the last change. Then use a recursive cte to test for changes. In the end you just need to format the string the way you want.