I have two tables document_header and document_allocation :

CREATE TABLE document_header 
(
    id int, 
    originalAmount decimal(5, 2), 
    doc_type char(2)
)

INSERT INTO document_header(id, originalAmount, doc_type) 
VALUES (1001, '200.00', 'PV'),
       (1002, '150.00', 'PV'),
       (1003, '300.00', 'IV'),
       (1004, '400.00', 'IV'),
       (1005, '600.00', 'IV')

CREATE TABLE document_allocation 
(
    id int, 
    allocatedto int, 
    allocatedfrom int, 
    allocatedamount decimal(5, 2)
)

INSERT INTO document_allocation 
VALUES (1, 1003, 1001, '100.00'),
       (2, 1004, 1001, '50.00'),
       (3, 1003, 1002, '50.00'),
       (4, 1005, 1001, '50.00'),
       (5, 1004, 1002, '50.00'),
       (6, 1003, 1001, '20.00')

I want to get the original document amount also the amount allocated.

Expected result:
| originalDocumentId | documentOriginalAmount | allocatedBy | allocatedamount |
| ------------ | ------------ | ------------ | ------------ |
| 1003 | 300.00 | 1001 | 120.00 |
| 1003 | 300.00 | 1002 | 50.00 |
| 1004 | 400.00 | 1001 | 50.00 |
| 1004 | 400.00 | 1002 | 50.00 |
| 1005 | 600.00 | 1001 | 30.00 |

SQL that returns the result as expected

SELECT
    originalDocument.id AS OriginalDocumentID,
    document_header.id AS allocatedBy,
    (SELECT SUM(document_header_a.originalAmount) 
     FROM document_header document_header_a 
     WHERE document_header_a.id = originalDocument.id),
    SUM(document_allocation.allocatedamount) AS amountAllocated
FROM
    document_header,
    document_allocation,
    document_header originalDocument
WHERE
    document_header.id = document_allocation.allocatedfrom AND
    originalDocument.id = document_allocation.allocatedto
GROUP BY
    originalDocument.id,
    document_header.id

But I don't want to use subquery in the select list, is there any other method?

I tried as below, but it double up the amount

SELECT
    originalDocument.id AS OriginalDocumentID,
    document_header.id AS allocatedBy,
    SUM(originalDocument.originalAmount) AS documentOriginalAmount,
    SUM(document_allocation.allocatedamount) AS amountAllocated
FROM
    document_header,
    document_allocation,
    document_header originalDocument
WHERE
    document_header.id = document_allocation.allocatedfrom AND
    originalDocument.id = document_allocation.allocatedto
GROUP BY
    originalDocument.id,
    document_header.id

Result of this SQL

Is there any other method that I can write my SQL so that I can skip using subquery?