Return opposite transaction value rows

I have this table structure and I want a query that needs to be returning opposite side columns values.

CREATE TABLE TransactionDetail
(
  ID NUMERIC NOT NULL PRIMARY KEY,
  TransactionCode bigint,
  COATitle NVARCHAR(50),
  DrAmount NUMERIC,
  CrAmount NUMERIC
);

INSERT INTO TransactionDetail VALUES (1, 1, 'Overtime', '2500', NULL);
INSERT INTO TransactionDetail VALUES (2, 1, 'Internship', NULL, '1500');
INSERT INTO TransactionDetail VALUES (3, 1, 'Medical', NULL, '1000');
INSERT INTO TransactionDetail VALUES (4, 2, 'Internship', '1150', NULL);
INSERT INTO TransactionDetail VALUES (5, 2, 'Overtime', NULL, '1150');
INSERT INTO TransactionDetail VALUES (6, 3, 'Overtime', '600', NULL);
INSERT INTO TransactionDetail VALUES (7, 3, 'Refreshment', '400', NULL);
INSERT INTO TransactionDetail VALUES (8, 3, 'Car Loan', '200', NULL);
INSERT INTO TransactionDetail VALUES (9, 3, 'Office Expenses', NULL, '1200');

If I pass parameter with value Overtime then it should return following rows

SELECT COATitle, DrAmount, CrAmount
FROM TransactionDetail
WHERE COATitle <> Overtime

Internship      NULL    1500
Medical         NULL    1000
Internship      1150    NULL
Office Expenses NULL    1200

The logic is against each transaction if the selected Account is on Debit side it should print the Credit side accounts and if the selected Account is on Credit side it should print Debit side accounts against that specific TransactionCode

Answer

The following code gives the desired result. It does that by checking to see whether the provided parameter is a debit or credit (or doesn’t exist) in the current transaction, then only displays the reverse as specified.

declare @Parameter nvarchar(50) = 'Overtime'

declare @Trans TABLE
(
  ID NUMERIC NOT NULL,
  TransactionCode bigint,
  COATitle NVARCHAR(50),
  DrAmount NUMERIC,
  CrAmount NUMERIC
);

INSERT INTO @Trans VALUES (1, 1, 'Overtime', '2500', NULL);
INSERT INTO @Trans VALUES (2, 1, 'Internship', NULL, '1500');
INSERT INTO @Trans VALUES (3, 1, 'Medical', NULL, '1000');
INSERT INTO @Trans VALUES (4, 2, 'Internship', '1150', NULL);
INSERT INTO @Trans VALUES (5, 2, 'Overtime', NULL, '1150');
INSERT INTO @Trans VALUES (6, 3, 'Overtime', '600', NULL);
INSERT INTO @Trans VALUES (7, 3, 'Refreshment', '400', NULL);
INSERT INTO @Trans VALUES (8, 3, 'Car Loan', '200', NULL);
INSERT INTO @Trans VALUES (9, 3, 'Office Expenses', NULL, '1200');

select TransactionCode, COATitle, DrAmount, CrAmount
from (
  SELECT TransactionCode, COATitle, DrAmount, CrAmount
    , case when exists (select 1 from @Trans T1 where T1.TransactionCode = T.TransactionCode and T1.COATitle = @Parameter and DrAmount is not null) then 1
      when exists (select 1 from @Trans T1 where T1.TransactionCode = T.TransactionCode and T1.COATitle = @Parameter and CrAmount is not null) then -1
      else 0 end TransSign
  FROM @Trans T
  WHERE COATitle <> @Parameter
) X
where (TransSign = -1 and DrAmount is not null)
or (TransSign = 1 and CrAmount is not null)