How to Order by With Union in Sql

Using group/order by with union clause in sql query

A union query may only have one order by clause.

If you are satisfied with ordering the whole resultset, you can remove all order by clauses and just keep the very last one, at the end of the query. It applies to the entire dataset that union generates.

Note that your UNIONs are equivalent to UNION ALLs - because the client name is different in each member - and should be phrased as such.

If, on the other hand, you want to order reach sub-result, then this is different. Basically you need a flag in each member, that can then be used to identify each group. The client name might be a good pick, so:

order by client_name, client_id

SQL - How to Order By in UNION query

Put a UNION ALL in a derived table. To keep duplicate elimination, do select distinct and also add a NOT EXISTS to second select to avoid returning same person twice if found in both tables:

select name, surname
from
(
    select distinct name, surname, 1 as tno
    from table1
    union all
    select distinct name, surname, 2 as tno
    from table2 t2
    where not exists (select * from table1 t1
                      where t2.name = t1.name
                        and t2.surname = t1.surname)
) dt
order by tno, surname, name

ORDER BY with UNION clause

You would need to put the union in a subquery, and order in the outer query. Also, the subquery needs to return the column that you want to use for sorting.

SELECT *
FROM (
    SELECT bo.id, bo.date, bo.status, bo2.u_registration_date
        FROM BO
        JOIN BO2 ON BO2.bo2stamp = BO.bostamp
        WHERE BO.date BETWEEN @inidate AND @findate AND BO.tabela1 IN ('INSTALED','CANCELED')
    UNION
        SELECT bo.id, bo.date, bo.status, bo2.u_registration_date
        FROM BO
        JOIN BO2 ON BO2.bo2stamp = BO.bostamp
        WHERE BO.date < @inidate AND BO.tabela1 NOT IN ('INSTALED','CANCELED')
) t
ORDER BY u_registration_date

Note that using UNION here does not make a lot of sense. The two members only differ by their date filter, so functionally your query is equivalent to just:

SELECT bo.id, bo.date, bo.status, bo2.u_registration_date
FROM BO
JOIN BO2 ON BO2.bo2stamp = BO.bostamp
WHERE BO.date < @findate AND BO.tabela1 NOT IN ('INSTALED','CANCELED')
ORDER BY bo2.u_registration_date

Mysql multiple ORDER BY with UNION

Try this

SELECT n.nid, max(na.gid) as mid,fav.field_date_posted_value, UNIX_TIMESTAMP(fav.field_date_posted_value) as pdate, 1 as ob FROM `node` as n
JOIN nodeaccess AS na ON na.nid = n.nid
LEFT JOIN field_data_field_date_posted AS fav ON fav.entity_id = n.nid
WHERE (na.gid IN(10,11) AND (n.status = '1') AND (n.type IN  ('article','blog', 'events', 'media', 'press_releases', 'expert_speak', 'feature', 'case_study', 'news', 'the_igtb_series', 'trend', 'white_paper')) )
GROUP BY n.nid 


UNION ALL

SELECT n.nid, max(na.gid) as mid,fav.field_date_posted_value, UNIX_TIMESTAMP(fav.field_date_posted_value) as pdate, 2 as ob FROM `node` as n
JOIN nodeaccess AS na ON na.nid = n.nid
LEFT JOIN field_data_field_date_posted AS fav ON fav.entity_id = n.nid
WHERE (na.gid IN(2) AND (n.status = '1') AND (n.type IN  ('article','blog', 'events', 'media', 'press_releases', 'expert_speak', 'feature', 'case_study', 'news', 'the_igtb_series', 'trend', 'white_paper')) )
GROUP BY n.nid  

ORDER BY ob ASC, pdate DESC

Fixed the order by date only base or group

Order by clause with Union in Sql Server

You need to use a sub-query with CASE in ORDER BY clause like this:

SELECT * FROM
(
  Select 0 PartyId, 'All' Name
  Union
  select PartyId, Name
  from PartyMst
) tbl
ORDER BY CASE WHEN PartyId = 0 THEN 0 ELSE 1 END
,Name

Output:

PARTYID	NAME
0	All
2	AAKASH & CO.
3	SHAH & CO.
1	SHIV ELECTRONICS

SQL: How to order a union alphabetically?

Ironically, in many databases, your query would return the values in alphabetical order. The sorting is done during the duplicate removal for union.

Of course, you can't depend on that. So, you should include an order by clause:

select name 
from Reviewer
union
select model
from Car
order by name;

The order by applies to the complete union. The column name comes from the first subquery.

How to ORDER BY one query only in a UNION ALL without subquery

The ORDER BY doesn't apply to just one SELECT, it applies to the whole result set, to the whole result after all rows are UNIONed. So, you need to include columns that will be used for sorting in each SELECT of the UNION ALL.

For example, the following is wrong syntax, because ORDER BY has to be after the last SELECT of the UNION.

SELECT CASE
           WHEN p.Category = 1
           THEN 'Very Active'
           WHEN p.Category = 2
           THEN 'Active '
           ELSE 'Departed'
       END AS Matrix
     , p.name AS [Name]
FROM #People p
ORDER BY p.Category

UNION ALL

SELECT 'Best Employee' AS Matrix
     , 'Alan' AS [Name]

Your second example from the question can be written in a simpler form, without sub-query:

SELECT CASE
           WHEN p.Category = 1
           THEN 'Very Active'
           WHEN p.Category = 2
           THEN 'Active '
           ELSE 'Departed'
       END AS Matrix
     , p.name AS [Name]
     , p.Category
FROM #People p

UNION ALL

SELECT 'Best Employee' AS Matrix
     , 'Alan' AS [Name]
     , NULL AS Category  --- or '' AS Category

ORDER BY Category;

In any case, the column Category has to be added in each SELECT statement of the UNION. I don't see how you can avoid it.

How to use ORDER BY inside UNION

Something like this should work in MySQL:

SELECT a.*
  FROM ( 
         SELECT ...  FROM ... ORDER BY ... 
       ) a
 UNION ALL 
SELECT b.*
  FROM ( 
         SELECT ...  FROM ... ORDER BY ... 
       ) b

to return rows in an order we'd like them returned. i.e. MySQL seems to honor the ORDER BY clauses inside the inline views.

But, without an ORDER BY clause on the outermost query, the order that the rows are returned is not guaranteed.

If we need the rows returned in a particular sequence, we can include an ORDER BY on the outermost query. In a lot of use cases, we can just use an ORDER BY on the outermost query to satisfy the results.

But when we have a use case where we need all the rows from the first query returned before all the rows from the second query, one option is to include an extra discriminator column in each of the queries. For example, add ,'a' AS src in the first query, ,'b' AS src to the second query.

Then the outermost query could include ORDER BY src, name, to guarantee the sequence of the results.

FOLLOWUP

In your original query, the ORDER BY in your queries is discarded by the optimizer; since there is no ORDER BY applied to the outer query, MySQL is free to return the rows in whatever order it wants.

The "trick" in query in my answer (above) is dependent on behavior that may be specific to some versions of MySQL.

Test case:

populate tables

CREATE TABLE foo2 (id INT PRIMARY KEY, role VARCHAR(20)) ENGINE=InnoDB;
CREATE TABLE foo3 (id INT PRIMARY KEY, role VARCHAR(20)) ENGINE=InnoDB;

INSERT INTO foo2 (id, role) VALUES 
  (1,'sam'),(2,'frodo'),(3,'aragorn'),(4,'pippin'),(5,'gandalf');
INSERT INTO foo3 (id, role) VALUES 
  (1,'gimli'),(2,'boromir'),(3,'elron'),(4,'merry'),(5,'legolas');

query

SELECT a.*
  FROM ( SELECT s.id, s.role
           FROM foo2 s
          ORDER BY s.role
       ) a
 UNION ALL
SELECT b.*
  FROM ( SELECT t.id, t.role
           FROM foo3 t
          ORDER BY t.role
       ) b

resultset returned

    id  role     
 ------  ---------
      3  aragorn  
      2  frodo    
      5  gandalf  
      4  pippin   
      1  sam      
      2  boromir  
      3  elron    
      1  gimli    
      5  legolas  
      4  merry

The rows from foo2 are returned "in order", followed by the rows from foo3, again, "in order".

Note (again) that this behavior is NOT guaranteed. (The behavior we observer is a side effect of how MySQL processes inline views (derived tables). This behavior may be different in versions after 5.5.)

If you need the rows returned in a particular order, then specify an ORDER BY clause for the outermost query. And that ordering will apply to the entire resultset.

As I mentioned earlier, if I needed the rows from the first query first, followed by the second query, I would include a "discriminator" column in each query, and then include the "discriminator" column in the ORDER BY clause. I would also do away with the inline views, and do something like this:

SELECT s.id, s.role, 's' AS src
  FROM foo2 s
 UNION ALL
SELECT t.id, t.role, 't' AS src
  FROM foo3 t
 ORDER BY src, role