How to change the orientation of a dataset using the SQL UNPIVOT function Using the UNPIVOT function in SQL we can convert from wide table with data in multiple columns, to a long narrow tabular format This is a very useful technique when you cannot control the format of the data being given to you https://youtu.be/TJrxo0D3070 #SQL #SQLTips #SQLUNPIVOT Music from https://www.bensound.com/

1. How to use UNPIVOT in SQL

2. The UNPIVOT function in SQL is used to
turn a dataset from columns to rows

3. From This…
A wide table of columns
Such as this….
To this…..
A table of Year, Month and days per month

4. Data Set Up
If you want to follow this example, you can run the following SQL to create the dataset used in this example
CREATE TABLE [dbo].[UNPIVOT_Example](
[year] [int] NULL,
[January] [int] NULL,
[February] [int] NULL,
[March] [int] NULL,
[April] [int] NULL,
[May] [int] NULL,
[June] [int] NULL,
[July] [int] NULL,
[August] [int] NULL,
[September] [int] NULL,
[October] [int] NULL,
[November] [int] NULL,
[December] [int] NULL
) ON [PRIMARY]
GO
INSERT [dbo].[UNPIVOT_Example] ([year], [January], [February], [March], [April], [May], [June], [July],
[August], [September], [October], [November], [December])
VALUES
(2018, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31),
(2019, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31),
(2020, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31),
(2021, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31),
(2022, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31)
GO

5. select Year, Month, days
from [dbo].[UNPIVOT_Example]
UNPIVOT
(days
for Month in
([January]
, [February]
, [March]
, [April]
, [May]
, [June]
, [July]
, [August]
, [September]
, [October]
, [November]
, [December])
)as dpm_unpivot
SQL UNPIVOT
Here is the SQL code and a breakdown of what
each part does
3. This is the final set of columns that we want to
output
2. This is the start of the UNPIVOT function,
We define the column ‘MONTH’ using the full
list of existing column names
‘days’ is the new name for the column of data
that we will generate from the UNPIVOT
1. Here we select each
of the columns of data
that we want to be
unpivoted

6. Use Cases
SQL UNPIVOT is very useful when the data you have to work with is already in a PIVOTED style
Quite often we come across that is provided to us in this way, usually as outputs from proprietary
systems
Converting these to tabular data sets makes working with the data much easier, and allows far
simpler work if you need to aggregate all the data by year

7. Hope you found this useful

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Timesavers, visit our website
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