How to convert many rows into Columns in SQL Server? - sql

Question

How would you convert a field that is stored as multiple rows into columns?
I listed the code below as well. Below is an example of what is needed but it can really go up to 20 columns. Thanks!
COL1 COL2 COL3
----------------
TEST 30 NY
TEST 30 CA
TEST2 10 TN
TEST2 10 TX
I would like the output to be :
COL1 COL2 COL3 COL4
------------------------
TEST 30 NY CA
TEST2 10 TN TX
select * from (
select
ID,
Name,
STORE,
Group,
Type,
Date,
State,
row_number() over(partition by ID, state order by Date desc) as rn
from
#test
) t
where t.rn = 1

Answer 1

declare #Table AS TABLE
(
Col1 VARCHAR(100) ,
Col2 INT ,
Col3 VARCHAR(100)
)
INSERT #Table
( Col1, Col2, Col3 )
VALUES
( 'TEST', 30 ,'NY' ),
( 'TEST', 30 ,'CA' ),
( 'TEST2', 10 ,'TN' ),
( 'TEST2', 10 ,'TX' )
SELECT
xQ.Col1,
xQ.Col2,
MAX(CASE WHEN xQ.RowNumber = 1 THEN xQ.Col3 ELSE NULL END) AS Col3,
MAX(CASE WHEN xQ.RowNumber = 2 THEN xQ.Col3 ELSE NULL END) AS Col4
FROM
(
SELECT * , RANK() OVER(PARTITION BY T.Col1,T.Col2 ORDER BY T.Col1,T.Col2,T.Col3) AS RowNumber
FROM #Table AS T
)AS xQ
GROUP BY
xQ.Col1,
xQ.Col2

Answer 2

There are multiple options to convert data from rows into columns. In SQL, you can use PIVOT to transform data from rows into columns.
CREATE table #tablename
(Id int, Value varchar(10), ColumnName varchar(15);
INSERT INTO #tablename
(ID, Value, ColumnName)
VALUES
(1, ‘Lucy’, 'FirstName'),
(2, ‘James’, ‘LastName’),
(3, ‘ABCDXX’, ‘Adress’),
(4, ’New York’, ‘City’),
(5, '8572685', ‘PhoneNo’);
select FirstName, LastName, Address, City, PhoneNo
from
(
select Value, ColumnName
from #tablename
) d
pivot
(
max(Value)
for ColumnName in (FirstName, LastName, Address, City, PhoneNo)
) piv;
Refer the below link for other options of transforming data from rows to columns:
https://www.sqlshack.com/multiple-options-to-transposing-rows-into-columns/