MySQL从多行选择值到一行

Question

I have a table with 4 rows with DateTime values saved into.

The query:

SELECT row1, row2, row3, row4 FROM table;

shows this result:

+------------+------------+------------+------------+
|    row1    |    row2    |    row3    |    row4    |
+------------+------------+------------+------------+
|01.01.2014  |null        |null        |31.12.2018  |
|null        |17.08.2015  |01.12.2050  |null        |
|02.01.2010  |null        |28.03.2067  |null        |
+------------+------------+------------+------------+

But I want to combine and order these dates into one row like:

+------------+
|    rows    |
+------------+
|01.01.2014  |
|02.01.2010  |
|17.08.2015  |
|01.12.2050  |
|28.03.2067  |
|31.12.2018  |
+------------+

What query do I have to use to get the result I want?

Thanks in advance

Answer 1

SELECT row1 AS rows FROM table WHERE row1 IS NOT NULL
UNION ALL
SELECT row2 AS rows FROM table WHERE row2 IS NOT NULL
UNION ALL
SELECT row3 AS rows FROM table WHERE row3 IS NOT NULL
UNION ALL
SELECT row4 AS rows FROM table WHERE row4 IS NOT NULL
ORDER BY rows DESC;

will do what you want I guess.

Do you have more info about the problem, eg table and column names.