How Can I Make Oracle Query Sort Order Dynamic? - oracle

Question

I have a Oracle procedure inside a package like this
PROCEDURE getEmployee
(
pinLanguage IN VARCHAR2,
pinPage IN NUMBER,
pinPageSize IN NUMBER,
pinSortColumn IN VARCHAR2,
pinSortOrder IN VARCHAR2,
poutEmployeeCursor OUT SYS_REFCURSOR
)
AS
BEGIN
OPEN poutEmployeeCursor FOR
SELECT * FROM (
SELECT EMPLOYEE_ID, USERNAME, FULL_NAME, DATE_OF_BIRTH, EMP.GENDER_ID, GEN_TR.GENDER, EMP.WORK_TYPE_ID, WT_TR.WORK_TYPE, SALARY, EMAIL, PROFILE_IMAGE,
ROW_NUMBER() OVER (ORDER BY EMPLOYEE_ID ASC) RN
FROM EMPLOYEES EMP
INNER JOIN GENDERS GEN ON EMP.GENDER_ID = GEN.GENDER_ID
LEFT JOIN GENDERS_MLD GEN_TR ON GEN.GENDER_ID = GEN_TR.GENDER_ID AND GEN_TR.LANGUAGE = pinLanguage
INNER JOIN WORK_TYPES WT ON EMP.WORK_TYPE_ID = WT.WORK_TYPE_ID
LEFT JOIN WORK_TYPES_MLD WT_TR ON WT.WORK_TYPE_ID = WT_TR.WORK_TYPE_ID AND WT_TR.LANGUAGE = pinLanguage
)
WHERE RN BETWEEN (((pinPage - 1) * pinPageSize) + 1) AND (pinPage * pinPageSize);
END;
I need to make the sort order of the above query dynamic
If I pass the text FullName to pinSortColumn parameter, it need to sort FULL_NAME column
If I pass the text DateOfBirth to pinSortColumn parameter, it need to sort DATE_OF_BIRTH column
If I pass the text Gender to pinSortColumn parameter, it need to sort GEN_TR.GENDER column
I can pass the text asc or desc to pinSortOrder parameter and the query need to be sorted accordingly.
Can you please help me to achieve this?

Answer 1

You can use separate order by for asc and desc as following:
ORDER BY
CASE pinSortOrder WHEN 'asc' THEN
CASE pinSortColumn
WHEN 'FullName' THEN FULL_NAME
WHEN 'DateOfBirth' THEN to_char(DATE_OF_BIRTH,'yyyymmddhh24miss')
WHEN 'Gender' THEN GEN_TR.GENDER
END
END,
CASE pinSortOrder WHEN 'desc' THEN
CASE pinSortColumn
WHEN 'FullName' THEN FULL_NAME
WHEN 'DateOfBirth' THEN to_char(DATE_OF_BIRTH,'yyyymmddhh24miss')
WHEN 'Gender' THEN GEN_TR.GENDER
END
END DESC
Let's say you have passed pinSortColumn as FullName and pinSortOrder as asc then order by clause will be ORDER BY FULL_NAME, NULL DESC (please note that default order will be asc so I have not write it in the code. Query will be ordered by FULL_NAME in ascending manner)
Now, If you have passed pinSortColumn as FullName and pinSortOrder as desc then order by clause will be ORDER BY NULL, FULL_NAME DESC.
Null will not impact ordering.
I hope it is clear now.
Cheers!!

Answer 2

Try this one:
WHERE ...
ORDER BY
CASE pinSortColumn
WHEN 'FullName' THEN FULL_NAME
WHEN 'DateOfBirth' THEN DATE_OF_BIRTH
WHEN 'Gender' THEN GEN_TR.GENDER
END;
However, I don't think you can use ASC, DESC is this way. You to create a dynamic query. For an OPEN ... FOR ... statement it is trivial:
sqlstr := 'SELECT * FROM (
SELECT EMPLOYEE_ID, USERNAME, FULL_NAME, DATE_OF_BIRTH, EMP.GENDER_ID, GEN_TR.GENDER, EMP.WORK_TYPE_ID, WT_TR.WORK_TYPE, SALARY, EMAIL, PROFILE_IMAGE,
ROW_NUMBER() OVER (ORDER BY EMPLOYEE_ID ASC) RN
FROM EMPLOYEES EMP
INNER JOIN GENDERS GEN ON EMP.GENDER_ID = GEN.GENDER_ID
LEFT JOIN GENDERS_MLD GEN_TR ON GEN.GENDER_ID = GEN_TR.GENDER_ID AND GEN_TR.LANGUAGE = :pinLanguage
INNER JOIN WORK_TYPES WT ON EMP.WORK_TYPE_ID = WT.WORK_TYPE_ID
LEFT JOIN WORK_TYPES_MLD WT_TR ON WT.WORK_TYPE_ID = WT_TR.WORK_TYPE_ID AND WT_TR.LANGUAGE = :pinLanguage
)
WHERE RN BETWEEN (((:pinPage - 1) * :pinPageSize) + 1) AND (:pinPage * :pinPageSize)
ORDER BY '
CASE pinSortColumn
WHEN 'FullName' THEN sqlstr := sqlstr || 'FULL_NAME ';
WHEN 'DateOfBirth' THEN sqlstr := sqlstr || 'DATE_OF_BIRTH ';
WHEN 'Gender' THEN sqlstr := sqlstr || 'GEN_TR.GENDER ';
END CASE;
sqlstr := sqlstr || pinSortOrder;
OPEN poutEmployeeCursor FOR sqlstr USING pinLanguage, pinLanguage, pinPage, pinPageSize, pinPage, pinPageSize;
Not in case you run Oracle 12c or newer you can use the Row Limiting Clause instead of dealing with row number.

Answer 3

You can avoid all these duplicated cases. Multiply row number by -1 when descending order is required:
order by
case pinSortOrder when 'desc' then -1 else 1 end *
row_number() over (
order by case pinSortColumn when 'FullName' then full_name end,
case pinSortColumn when 'Gender' then gender end,
case pinSortColumn when 'DateOfBirth' then date_of_birth end)
dbfiddle demo
Also this way you do not have to convert data the same type, no need to use to_char.