How to Transpose a SQL Table with Multiple Columns?

Transpose a SQL table with multiple columns

Question:

You need to transpose a SQL table with multiple columns, for example:

<code>Day  A  B 
---------
Mon  1  2
Tue  3  4
Wed  5  6
Thu  7  8
Fri  9  0</code>

Transpose to the following format:

<code>Value Mon Tue Wed Thu Fri 
--------------------------
A      1   3   5   7   9
B      2   4   6   8   0</code>

Solution:

To transpose a table with multiple columns, you can use the UNPIVOT and PIVOT functions together.

1. UNPIVOT: Convert multiple columns (A, B) into rows and add a column for column names:

<code class="language-sql">select day, col, value
from yourtable
unpivot
(
  value
  for col in (A, B)
) unpiv</code>

2. PIVOT: Convert "day" value to column and aggregate "value" column:

<code class="language-sql">select *
from
(
  select day, col, value
  from yourtable
  unpivot
  (
    value
    for col in (A, B)
  ) unpiv
) src
pivot
(
  max(value)
  for day in (Mon, Tue, Wed, Thu, Fri)
) piv</code>

This will generate the required transposed table.

Additional notes:

• If your SQL Server version is 2008 or higher, you can use CROSS APPLY and VALUES instead of the UNPIVOT function to transpose the data:

<code class="language-sql">select *
from
(
  select day, col, value
  from yourtable
  cross apply
  (
    values ('A', ACalls), ('B', BCalls)
  ) c (col, value)
) src
pivot
(
  max(value)
  for day in (Mon, Tue, Wed, Thu, Fri)
) piv</code>

• To perform the transpose operation on your specific query, you can use code similar to the following structure:

<code class="language-sql">select *
from
(
  select LEFT(datename(dw,datetime),3) as DateWeek, col, value
  from DataTable 
  cross apply 
  (
    values ('A', ACalls), ('B', BCalls)
  ) c (col, value)
) src
pivot
(
  sum(value)
  for dateweek in (Mon, Tue, Wed, Thu, Fri)
) piv</code>

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