Si je n'ai rien raté :
WITH ranked AS (
SELECT
ChangeDate,
ColPK,
Col1,
Col2,
Col3,
Col4,
Col5,
OverallRank = ROW_NUMBER() OVER (PARTITION BY ColPK ORDER BY ChangeDate),
Col1Rank = ROW_NUMBER() OVER (PARTITION BY ColPK, Col1 ORDER BY ChangeDate),
Col2Rank = ROW_NUMBER() OVER (PARTITION BY ColPK, Col2 ORDER BY ChangeDate),
Col3Rank = ROW_NUMBER() OVER (PARTITION BY ColPK, Col3 ORDER BY ChangeDate),
Col4Rank = ROW_NUMBER() OVER (PARTITION BY ColPK, Col4 ORDER BY ChangeDate),
Col5Rank = ROW_NUMBER() OVER (PARTITION BY ColPK, Col5 ORDER BY ChangeDate)
FROM AuditTable
)
, ranked2 AS (
SELECT
ChangeDate,
ColPK,
Col1,
Col2,
Col3,
Col4,
Col5,
Col1Group = RANK() OVER (PARTITION BY ColPK, Col1 ORDER BY OverallRank - Col1Rank),
Col2Group = RANK() OVER (PARTITION BY ColPK, Col2 ORDER BY OverallRank - Col2Rank),
Col3Group = RANK() OVER (PARTITION BY ColPK, Col3 ORDER BY OverallRank - Col3Rank),
Col4Group = RANK() OVER (PARTITION BY ColPK, Col4 ORDER BY OverallRank - Col4Rank),
Col5Group = RANK() OVER (PARTITION BY ColPK, Col5 ORDER BY OverallRank - Col5Rank),
Col1Rank = ROW_NUMBER() OVER (PARTITION BY ColPK, Col1, OverallRank - Col1Rank ORDER BY ChangeDate),
Col2Rank = ROW_NUMBER() OVER (PARTITION BY ColPK, Col2, OverallRank - Col2Rank ORDER BY ChangeDate),
Col3Rank = ROW_NUMBER() OVER (PARTITION BY ColPK, Col3, OverallRank - Col3Rank ORDER BY ChangeDate),
Col4Rank = ROW_NUMBER() OVER (PARTITION BY ColPK, Col4, OverallRank - Col4Rank ORDER BY ChangeDate),
Col5Rank = ROW_NUMBER() OVER (PARTITION BY ColPK, Col5, OverallRank - Col5Rank ORDER BY ChangeDate)
FROM ranked
),
unpivoted AS (
SELECT
r.ChangeTime,
r.ColPK,
x.ColName,
ColRank = CASE x.Colname
WHEN 'Col1' THEN Col1Group
WHEN 'Col2' THEN Col2Group
WHEN 'Col3' THEN Col3Group
WHEN 'Col4' THEN Col4Group
WHEN 'Col5' THEN Col5Group
END,
Value = CASE x.Colname
WHEN 'Col1' THEN CONVERT(nvarchar(100), r.Col1)
WHEN 'Col2' THEN CONVERT(nvarchar(100), r.Col2)
WHEN 'Col3' THEN CONVERT(nvarchar(100), r.Col3)
WHEN 'Col4' THEN CONVERT(nvarchar(100), r.Col4)
WHEN 'Col5' THEN CONVERT(nvarchar(100), r.Col5)
END
FROM ranked2 r
INNER JOIN (VALUES ('Col1'), ('Col2'), ('Col3'), ('Col4'), ('Col5')) x (ColName)
ON x.ColName = 'Col1' AND Col1Rank = 1
OR x.ColName = 'Col2' AND Col2Rank = 1
OR x.ColName = 'Col3' AND Col3Rank = 1
OR x.ColName = 'Col4' AND Col4Rank = 1
OR x.ColName = 'Col5' AND Col5Rank = 1
)
SELECT
new.ChangeTime,
new.ColPK,
new.ColName,
old.Value AS OldValue,
new.Value AS NewValue
FROM unpivoted new
LEFT JOIN unpivoted old
ON new.ColPK = old.ColPK
AND new.ColName = old.ColName
AND new.ColRank = old.ColRank + 1
Fondamentalement, l'idée est de classer des groupes contigus de valeurs identiques et de choisir les premières occurrences de chaque valeur. Cela est fait pour chaque colonne dont les valeurs sont auditées, et les colonnes ne sont pas pivotées dans le processus. Ensuite, l'ensemble de lignes non pivoté est joint à lui-même, c'est-à-dire que pour chaque PK et nom de colonne, chaque ligne est mise en correspondance avec son prédécesseur (en fonction du classement) pour obtenir l'ancienne valeur dans la même ligne pour l'ensemble de résultats final.
