My database like this: table name: messages
| receive | transmit |
---------------------
| 1 | 5 |
| 1 | 6 |
| 1 | 3 |
| 3 | 1 |
| 4 | 1 |
| 2 | 3 |
| 4 | 6 |
| 7 | 9 |
And i am trying to get all unique id's from each table. So my answer must be 1, 3, 4, 5, 6.
if i use SELECT DISTINCT receive FROM messages ;
i will get 1, 3 ,4
if i use SELECT DISTINCT transmit FROM messages ;
i will get 1, 3 ,5, 6
how do i get 1, 3, 4, 5, 6?
The default for UNION
is DISTINCT
:
SELECT "from" FROM tableX
UNION
SELECT "to" FROM tableX;
SELECT DISTINCT `fr_om` FROM `table`
UNION
SELECT DISTINCT `to` FROM `table` WHERE `to` NOT IN (SELECT DISTINCT `fr_om` FROM table)
Updated : you can just use UNION to remove the duplicates from your result set.
SELECT DISTINCT `fr_om` FROM `table`
UNION
SELECT DISTINCT `to` FROM `table`
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