Select dynamic columns in a table in sql server - sql

Question

I have data in the table that contains the surcharge price of many carriers in many years. Each carrier will have 12 months.
CARRIER_ID YEAR MONTH RATE
DHL 2021 April 16.5
DHL 2021 August 18.5
DHL 2021 December 0
DHL 2021 February 14
DHL 2021 January 12.5
DHL 2021 July 17.75
DHL 2021 June 17
DHL 2021 March 15
DHL 2021 May 17
DHL 2021 November 0
DHL 2021 October 0
DHL 2021 September 0
FedEx 2021 April 16.5
FedEx 2021 August 17.5
FedEx 2021 December 0
FedEx 2021 February 14.5
FedEx 2021 January 13.5
FedEx 2021 July 17.5
FedEx 2021 June 17
FedEx 2021 March 16
FedEx 2021 May 16.5
FedEx 2021 November 0
FedEx 2021 October 0
FedEx 2021 September 0
And I want to make a query in SQL server to get data like this.
Please note that: The data need to group by the year(exp: 2021)
Month DHL FedEx
January 12.50% 13.50%
February14.00% 14.50%
March 15.00% 16.00%
April 16.50% 16.50%
May 17.00% 16.50%
June 17.00% 17.00%
July 17.75% 17.50%
August 18.50% 17.50%
September0 0
October 0 0
November0 0
December0 0
I did search in google but can not find the solution.
Pls give me how to do it.
Thank you so much.

Answer 1

If you do know your list of carriers, you can do it like this with standard sql
select
t.YEAR,
t.MONTH,
max(case when t.CARRIER_ID = 'DHL' then t.RATE else NULL) as DHL,
max(case when t.CARRIER_ID = 'FedEx' then t.RATE else NULL) as FedEx
from your_table t
group by t.YEAR, t.MONTH
order by t.YEAR, t.MONTH
YEAR and MONTH are usually reserved words, so it's not recommended to use them in your data.