MySQL UNION with Multiple ORDER BY

MySQL

I have tried to make this work in multiple forms but none have been successful. I need to read an int from my table to order my data as desired. I have previously gotten this to work as multiple queries but Im hoping to do it all in one now.

    SELECT * FROM (
        (SELECT * FROM table_a WHERE int_a <= *myint* ORDER BY int_a DESC)
        UNION 
        (SELECT * FROM table_a WHERE int_a >= *myint* ORDER BY int_a DESC)
    ) uniontable

MySQL 5.7

Best Answer

I'm not exactly sure what you re trying to achieve, but if you want the rows from the first leg to be ordered first, then you can add an attribute that determines from which leg the row belongs:

select myint from (
    select 1 as origin, myint from table_a where myint < 5
    union
    select 2 as origin, myint from table_a where myint > 5
) as t
order by origin, myint desc;

myint
4
3
2
1
9
8
7
6

Fiddle

Related Solutions

MySql: #1221 – Incorrect usage of UNION and ORDER BY

There are several ways to pass the IN / LIMIT limitation and the UNION / ORDER BY syntax requirements.

Wrap the Union in a derived table:

SELECT * FROM comment AS tbl WHERE sscm_id IN
  ( SELECT sscm_id
    FROM     
      ( ( SELECT sscm_id FROM comment AS t1 WHERE t1.sscm_oid = 4 
          ORDER BY t1.sscm_id DESC LIMIT 3)
      UNION  ALL
        ( SELECT sscm_id FROM comment AS t2 WHERE t2.sscm_oid = 3 
          ORDER BY t2.sscm_id DESC LIMIT 3)
      ) AS tmp 
  ) ;

Use JOIN instead of WHERE / IN:
UNION is required here instead of UNION ALL to avoid duplicates

SELECT tbl.* 
FROM comment AS tbl 
    JOIN 
        ( ( SELECT sscm_id FROM comment AS t1 WHERE t1.sscm_oid = 4 
            ORDER BY t1.sscm_id DESC LIMIT 3)
        UNION 
          ( SELECT sscm_id FROM comment AS t2 WHERE t2.sscm_oid = 3 
            ORDER BY t2.sscm_id DESC LIMIT 3)
        ) AS tmp 
      ON tmp.sscm_id = tbl.sscm_id ;

Mysql – Selecting multiple columns from multiple rows in one column (subquery?)

You need to use GROUP_CONCAT to aggregate the citizen names first. Then use CONCAT

SELECT CONCAT(id,' # ',name,' # ',citizens) listing FROM
(
    SELECT A.id,A.name,GROUP_CONCAT(B.name,' ',B.surname) citizens
    FROM city A INNER JOIN citizen B
    ON A.id = B.city_id GROUP BY A.id,A.name
) AA;

Here is the SQL Fiddle to prove it : http://sqlfiddle.com/#!2/9f4b3/1

If the names become too long due to truncation, you will have to extend GROUP_CONCAT's maximum length. To set it to 16K, run the following:

SET group_concat_max_len = 1024 * 16;
SET GLOBAL group_concat_max_len = 1024 * 16;

First line is for the session, the second is for all new DB Connections.

Best Answer

Related Solutions

MySql: #1221 – Incorrect usage of UNION and ORDER BY

Mysql – Selecting multiple columns from multiple rows in one column (subquery?)

Related Question