Let’s say I have columns `a, b c, d`

in a table in a MySQL database. What I’m trying to do is to select the distinct values of ALL of these 4 columns in my table (only the distinct values). I tried stuff like:

```
SELECT DISTINCT a,b,c,d FROM my_table;
SELECT DISTINCT a,b,c,d FROM my_table GROUP BY a,b,c,d;
```

None of those worked. Can anybody help out here?

Thank you

**NOTE** I want the distinct values of the columns `a, b, c d`

separately. Not the distinct combination of values

can this help?

```
select
(SELECT group_concat(DISTINCT a) FROM my_table) as a,
(SELECT group_concat(DISTINCT b) FROM my_table) as b,
(SELECT group_concat(DISTINCT c) FROM my_table) as c,
(SELECT group_concat(DISTINCT d) FROM my_table) as d
```

I know that the question is too old, anyway:

```
select a, b from mytable group by a, b
```

will give your all the combinations.

Taking a guess at the results you want so maybe this is the query you want then

```
SELECT DISTINCT a FROM my_table
UNION
SELECT DISTINCT b FROM my_table
UNION
SELECT DISTINCT c FROM my_table
UNION
SELECT DISTINCT d FROM my_table
```

Another simple way to do it is with `concat()`

```
SELECT DISTINCT(CONCAT(a,b)) AS cc FROM my_table GROUP BY (cc);
```

Both your queries are correct and should give you the right answer.

I would suggest the following query to troubleshoot your problem.

```
SELECT DISTINCT a,b,c,d,count(*) Count FROM my_table GROUP BY a,b,c,d
order by count(*) desc
```

That is add count(*) field. This will give you idea how many rows were eliminated using the group command.

This will give DISTINCT values across all the columns:

```
SELECT DISTINCT value
FROM (
SELECT DISTINCT a AS value FROM my_table
UNION SELECT DISTINCT b AS value FROM my_table
UNION SELECT DISTINCT c AS value FROM my_table
) AS derived
```