How to convert a single row into one column? - valueconverter

Question

How to convert columns of one row into one row each?
Having data in table as below:
+------+------+------+------+
| col1 | col2 | col3 | col4 |
+------+------+------+------+
| a1 | a2 | a3 | a4 |
+------+------+------+------+
required output: all values in the row should go in single column as below.
+---------------+
| All_cols |
+---------------+
| a1,a2,a3,a4 |
+---------------+
Like in image: Here mytable always have one record, so I need the output as below.
want to avoid below sql as it requires multiple joins:
select a1.name from accounts a1 where a1.id='658f3b73-8260-5a7a-ae7e-54c25deded36'
union
Select a2.name from accounts a1
left join accounts a2 on a1.id=a2.parent_id where a1.id='658f3b73-8260-5a7a-ae7e-54c25deded36'
union
Select a3.name from accounts a1
left join accounts a2 on a1.id=a2.parent_id
left join accounts a3 on a2.id=a3.parent_id where a1.id='658f3b73-8260-5a7a-ae7e-54c25deded36'
union
Select a4.name from accounts a1
left join accounts a2 on a1.id=a2.parent_id
left join accounts a3 on a2.id=a3.parent_id
left join accounts a4 on a3.id=a4.parent_id where a1.id='658f3b73-8260-5a7a-ae7e-54c25deded36'
union
Select a5.name from accounts a1
left join accounts a2 on a1.id=a2.parent_id
left join accounts a3 on a2.id=a3.parent_id
left join accounts a4 on a3.id=a4.parent_id
left join accounts a5 on a4.id=a5.parent_id where a1.id='658f3b73-8260-5a7a-ae7e-54c25deded36'

Answer 1

You could make a UNION on four single calls
SELECT col1 FROM mytable
UNION
SELECT col2 FROM mytable
UNION
SELECT col3 FROM mytable
UNION
SELECT col4 FROM mytable
will output
You say that
mytable always have one record.
Be aware that if you have more than one record, it's wise to use the same WHERE condition on each SELECT statement above.