从一个表中的同一表的2列中检索DISTINCT值

Question

I would like to take two columns of data in the same table, and return the unique records from both in an ordered list. I tried this:

SELECT DISTINCT column1,column2 FROM table ORDER BY column1 ASC

However this obviously returns both columns, column2 has duplicates and its ordered by column 1.

I want to receive something like

Abcde [column1]
Beefr [column2]
Ceeed [column1]
Desss [column1]
...etc

Is this possible? I'm using PHP too if this helps?

Answer 1

You need to do a union

select distinct column1 v from table union select distinct column2 v from table order by v

Answer 2

tbl1 COL1 | tbl2 COL2 | NEWCOL (The conclusion to be us)

---

a ------------- a ------------- a

b ------------- b ------------- b

c ------------- d ------------- c

e ------------- f ------------- d

------------- ------------- e

------------- ------------- f

Auto DISTINCT, this work.

$Sql="SELECT COL1 AS NEWCOL FROM tbl1 UNION SELECT COL2 FROM tbl2 ORDER BY NEWCOL ASC";

    $q=mysql_query($Sql) or die(mysql_error());
        while($rs=mysql_fetch_array($q)){
            echo $rs['NEWCOL'].'<br/>';
        }

Answer 3

You could use something like this (sintax depends on db engine):

SELECT DISCTINCT column
FROM
   ( 
    SELECT column1 as column FROM table
    UNION
    SELECT column2 as column FROM table
   )
ORDER BY column ASC

Refer to you dbms manual to check sintax on UNION clause