Re: Column headings in csv

On 23-5-2020 01:47, Richard Yates wrote:
> On Sun, 02 Feb 2020 13:57:48 +0100, Kees Nuyt <[email protected]>
> wrote:
> 

>> Yeah, you can only ORDER the result of the UNION, not on of its
>> parts.
> 
> Actually you can if you order each part and then set a limit. Recently
> I found this out and am using this (in a php application).
> 
> (Distribution sites are each assigned to one of several districts. The
> query pulls out the ones from one of the districts to list first at
> the top of a dropdown menu, and then lists the remaining ones.)
> 
> $distsitesq="
> (select distsite, name from distsites
> where ID_district=$ID_district
> order by name limit 999) union
> (select distsite, name from distsites
> where ID_district<>$ID_district
> order by name limit 999)";
> 
> 999 is chosen because in this example it is far larger than the
> distsites table will ever be. Setting the limit enforces the ordering
> of each part.
> 
> 

This is not right, it might give look like the correct result, but it is 
not guaranteed the correct result.

The correct (SQL) way to do this is like this:

select 1 as x,distsite, name from distsites
  where ID_district=$ID_district
  union
  select 2 as x, distsite, name from distsites
  where ID_district<>$ID_district
order by x,name