how to write a query to show values in separate date columns

Question

I have some data

John has sum of money for the year = 30

Larry has sum of money for the year = 60.

Usually, the results in the database show like this...

id	name	yearly sum
1	john	30
2	larry	60

so I want it broken down like this without personally inserting the values myself

id	name	jan	feb	mar	apr	may
1	john	10	5	4	6	5
2	larry	20	15	4	6	15

sample of the original data.

Employee	company	contributions	months contributed on
John	Walmart	10	January
John	Walmart	5	Feb
John	Walmart	4	March
John	Walmart	6	Apr
John	Walmart	5	May
Larry	Amazon	20	January
Larry	Amazon	15	Feb
Larry	Amazon	4	March
Larry	Amazon	6	Apr
Larry	Amazon	15	May

Answer 1

This is commonly referred to as a pivot. I'm not a PostrgreSQL expert, but this style of query is pretty easy to effect in virtually all SQL-compliant database management systems.

First, we'll create a table:

CREATE TABLE contributions
(
 Employee varchar(50)
 , Company varchar(50)
 , Contributions int
 , Contribution_Month varchar(10)
);

And insert some values into it:

INSERT INTO contributions (Employee, Company, Contributions, Contribution_Month)
VALUES 
 ('John', 'Walmart', 10, 'January')
 , ('John', 'Walmart', 5, 'February')
 , ('Larry', 'Amazon', 20, 'January')
 , ('Larry', 'Amazon', 15, 'February')

Here's the "pivot" bit:

SELECT
 totals.Employee
 , SUM(totals.January) AS January
 , SUM(totals.February) AS February
FROM (
 SELECT
 Employee
 , CASE WHEN Contribution_Month = 'January' THEN Contributions ELSE 0 END AS January
 , CASE WHEN Contribution_Month = 'February' THEN Contributions ELSE 0 END AS February
 FROM contributions
 ) totals
GROUP BY totals.Employee;

And the results:

employee	january	february
John	10	5
Larry	20	15

I've only included January and February since the other months would just be rote repetition, but you should be able to extend it to include the other months without much work.

PostgreSQL offers the crosstab table function to produce a pivot table, which you construct like this:

SELECT 
 ct.Employee
 , ct.January
 , ct.February
FROM 
 crosstab
 (
 'SELECT Employee, Contribution_Month, Contributions FROM contributions'
 ) AS ct
 (
 employee varchar(50)
 , January int
 , February int
 );

The output looks exactly the same as my example above, so I'll not repeat it here.

Here is a DB Fiddle for the above minimal, complete and verifiable example.