Непривитый противЗапросы объединения в T-SQL 2008
-
11-09-2019 - |
Вопрос
База данных, из которой я извлекаю данные, имеет структуру таблицы, подобную этой
Таблица:Продажи клиентам
ClientSalesId int identity (1, 1) (PK)
ClientId int (FK)
TermId int (FK)
StudentType1Population int
StudentType1Adjustment int
StudentType1Sales int
StudentType1SalesAdjustment int
StudentType2Population int
StudentType2Adjustment int
StudentType2Sales int
StudentType2SalesAdjustment int
StudentType3Population int
StudentType3Adjustment int
StudentType3Sales int
StudentType3SalesAdjustment int
StudentType4Population int
StudentType4Adjustment int
StudentType4Sales int
StudentType4SalesAdjustment int
StudentType5Population int
StudentType5Adjustment int
StudentType5Sales int
StudentType5SalesAdjustment int
Я должен отобразить его без привязки в отчете следующим образом
Для ClientID = 1 и Term Id = 1
Population PopulationAdjustment Sales SalesAdjustment StudentType1 313 18 123 22 StudentType2 233 14 156 33 StudentType3 234 12 112 41 StudentType4 233 13 198 29 StudentType5 343 10 134 36
Я могу сделать это двумя способами
SELECT
'StudentType1' as DemographicType
StudentType1Population as Population,
StudentType1Adjustment as PopulationAdjustment,
StudentType1Sales as Sales,
StudentType1SalesAdjustment as SalesAdjustment,
FROM ClientSales
WHERE 1=1
AND ClientId = 1
AND TermId = 1
UNION
SELECT
'StudentType2' as DemographicType
StudentType2Population as Population,
StudentType2Adjustment as PopulationAdjustment,
StudentType2Sales as Sales,
StudentType2SalesAdjustment as SalesAdjustment,
FROM ClientSales
WHERE 1=1
AND ClientId = 1
AND TermId = 1
-- yada yada yada for the rest of the types...........
или
SELECT
ClientId,
Population
FROM
(
SELECT
ClientId,
StudentType1Population,
StudentType2Population,
StudentType3Population,
StudentType4Population,
StudentType5Population
FROM ClientSales
) PVTPopulation
UNPIVOT
(
Population for StudentType IN
(
StudentType1Population,
StudentType2Population,
StudentType3Population,
StudentType4Population,
StudentType5Population
)
) as UnPvtPopulation
INNER JOIN
(
SELECT
ClientId,
StudentType1PopulationAdjustment,
StudentType2PopulationAdjustment,
StudentType3PopulationAdjustment,
StudentType4PopulationAdjustment,
StudentType5PopulationAdjustment
FROM ClientSales
) PVTPopulation
UNPIVOT
(
PopulationAdjustment for StudentType IN
(
StudentType1PopulationAdjustment,
StudentType2PopulationAdjustment,
StudentType3PopulationAdjustment,
StudentType4PopulationAdjustment,
StudentType5PopulationAdjustment
)
) as UnPvtPopulationAdjustment
ON UnPvtPopulationAdjustment.ClientSalesId = UnPvtPopulation.ClientSalesId
AND REPLACE (UnPvtPopulationAdjustment.StudentType, 'PopulationAdjustment', '') = REPLACE (UnPvtPopulation.StudentType, 'Population', '')
INNER JOIN
(
SELECT
ClientId,
StudentType1Sales,
StudentType2Sales,
StudentType3Sales,
StudentType4Sales,
StudentType5Sales
FROM ClientSales
) PVTSales
UNPIVOT
(
Sales for StudentType IN
(
StudentType1Sales,
StudentType2Sales,
StudentType3Sales,
StudentType4Sales,
StudentType5Sales
)
) as UnPvtSales
ON UnPvtSales.ClientSalesId = UnPvtPopulation.ClientSalesId
AND REPLACE (UnPvtSales.StudentType, 'Sales', '') = REPLACE (UnPvtPopulation.StudentType, 'Population', '')
Итак, вот вопросы:
- В качестве наилучшей практики, должен ли я использовать UNPIVOT или UNION
- Есть ли лучший способ написать этот UNPIVOT?
Решение
Я обнаружил, что UNPIVOT - это то же самое, что предложение where..вы можете использовать столько, сколько вам нужно
SELECT Col1, Col2, Unp1, Unp2, Unp3
FROM TBL
UNPIVOT (XX For Unp1 (ColXX1, ColXX2))
UNPIVOT (YY For Unp2 (ColYY1, ColYY2))
UNPIVOT (ZZ For Unp2 (ColZZ1, ColZZ2))
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