Keep ORDER BY after UNION [duplicate] - mysql

Question

This question already has answers here:
How can I order entries in a UNION without ORDER BY?
(7 answers)
Closed 4 years ago.
I have a problem to solve.
I have a table Occupationswith Name and Occupation.
My task is to:
1.Query an alphabetically ordered list of all names in OCCUPATIONS, immediately followed by the first letter of each profession as a parenthetical (i.e.: enclosed in parentheses). For example: AnActorName(A), ADoctorName(D), AProfessorName(P), and ASingerName(S).
query the number of ocurrences of each occupation in OCCUPATIONS. Sort the occurrences in ascending order, and output them in the following format:
There are a total of [occupation_count] [occupation]s.
If more than one Occupation has the same they should be ordered alphabetically.
I am almost done with the query
SELECT TEMP.CON1
FROM (
SELECT NAME, CONCAT(NAME,'(', LEFT(OCCUPATION, 1),')') AS CON1
FROM OCCUPATIONS
ORDER BY NAME
) AS TEMP
UNION
SELECT TEMP2.CON2
FROM (
SELECT COUNT(*) AS NR, CONCAT('THERE ARE A TOTAL OF ', COUNT(OCCUPATION),' ', OCCUPATION, 's') AS CON2
FROM OCCUPATIONS
GROUP BY OCCUPATION
ORDER BY NR, OCCUPATION
) AS TEMP2
but I don't know how to keep the order of the first section after the two sections are united.
If anyone knows the answer I would be superglad for sharing.

Answer 1

SELECT CON
FROM
(
SELECT 1 as SEQ, 0 as NR, NAME ,TEMP.CON1 as CON
FROM (
SELECT NAME, CONCAT(NAME,'(', LEFT(OCCUPATION, 1),')') AS CON1
FROM OCCUPATIONS
ORDER BY NAME -- don't need
) AS TEMP
UNION
SELECT 2, NR, null, TEMP2.CON2
FROM (
SELECT COUNT(*) AS NR, CONCAT('THERE ARE A TOTAL OF ', COUNT(OCCUPATION),' ', OCCUPATION, 's') AS CON2
FROM OCCUPATIONS
GROUP BY OCCUPATION
ORDER BY NR, OCCUPATION -- don't need
) AS TEMP2 ) T
ORDER BY SEQ, NR, NAME, CON

Answer 2

UNION ALL would keep the order, and would work just as well in this case as your result sets are totally different.
The difference between union and union all is that UNION removes duplicates, which causes reordering, where UNION ALL simply adds the next set of results to the end of the existing result set. Since you are manipulating the strings on both selects, there is no real chance of there being duplicates in the results between TEMP and TEMP2. This will also get rid of some of the cost of the query, since UNION is more expensive than UNION ALL, as it needs to check for duplicates.
SELECT TEMP.CON1
FROM (
SELECT NAME, CONCAT(NAME,'(', LEFT(OCCUPATION, 1),')') AS CON1
FROM OCCUPATIONS
ORDER BY NAME
) AS TEMP
UNION ALL
SELECT TEMP2.CON2
FROM (
SELECT COUNT(*) AS NR, CONCAT('THERE ARE A TOTAL OF ', COUNT(OCCUPATION),' ', OCCUPATION, 's') AS CON2
FROM OCCUPATIONS
GROUP BY OCCUPATION
ORDER BY NR, OCCUPATION
) AS TEMP2
This being said, the way I read the instructions, I wouldn't expect both results to be desired in the same result set.