I think the easiest is to create a new logical column with the correct
ordering, something like:
SELECT *, IF(update != '', update, date) AS o
FROM my_table ORDER BY o DESC;
I note that both 'update' and 'date' are reserved works :)
Also worth noting that this cannot be assigned an index and is therefore
only good for small amounts of data.
---------------------
If you have lots of data then you need a better solution. Set 'update'
to NULL where there is no value and add the key:
KEY(update,date)
Then order by this key:
ORDER BY update DESC, date DESC.
Which when I try it gives:
+-----+--------+----------+
| num | date | update |
+-----+--------+----------+
| 5 | 40 | 90 |
| 2 | 10 | 60 |
| 6 | 50 | NULL |
| 4 | 30 | NULL |
| 3 | 20 | NULL |
| 1 | 1 | NULL |
+-----+--------+----------+
Ben
Richard wrote:
Hello,
I've got a table which containes two date colomns.
The first one is called `date` and the second `update`
In the first one I put the ticket creation date, and on update I add or
change the update value.
So the update colomn does not contain a value until the first update has
been done.
I would like to order the tickets by their last update value. And if
this value does not exist use the date value.
at the moment I use this :
ORDER BY `date` DESC"
and I would like to replace it by something like this :
ORDER (IF `update`!= '' BY UPDATE ELSE BY DATE)
I know this code is completly wrong, just to try and show you what I
need ...
Here is an example of what I want to achieve
num | date | update
-------------------------------------------
1 | 1 |
2 | 10 | 60
3 | 20 |
4 | 30 |
5 | 40 | 90
6 | 50 |
The required result would be :
num | date | update
-------------------------------------------
5 | 40 | 90
2 | 10 | 60
6 | 50 |
4 | 30 |
3 | 20 |
1 | 1 |
Thanks in advance :)
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