Sorting string column containing numbers in SQL?

Solution 1:

Going on the assumption it's always WORD_space_NUMBER this should work:

SELECT   *
FROM     table
ORDER BY CAST(SUBSTRING(column,LOCATE(' ',column)+1) AS SIGNED)

Use POSITION to find the space, SUBSTRING to grab the number after it, and CAST to make it a comparable value.

If there is a different pattern to the column, let me know and I'll try to devise a better work-around.

EDIT Proven to work:

mysql> INSERT INTO t (st) VALUES ('a 1'),('a 12'),('a 6'),('a 11');
Query OK, 4 rows affected (0.00 sec)
Records: 4  Duplicates: 0  Warnings: 0

mysql> SELECT * FROM t ORDER BY st;
+----+------+
| id | st   |
+----+------+
|  1 | a 1  |
|  4 | a 11 |
|  2 | a 12 |
|  3 | a 6  |
+----+------+
4 rows in set (0.00 sec)

mysql> SELECT * FROM t ORDER BY CAST(SUBSTRING(st,LOCATE(' ',st)+1) AS SIGNED);
+----+------+
| id | st   |
+----+------+
|  1 | a 1  |
|  3 | a 6  |
|  4 | a 11 |
|  2 | a 12 |
+----+------+

mysql> INSERT INTO t (st) VALUES ('b 1'),('b 12'),('b 6'),('b 11');
Query OK, 4 rows affected (0.00 sec)
Records: 4  Duplicates: 0  Warnings: 0

mysql> SELECT * FROM t ORDER BY CAST(SUBSTRING(st,LOCATE(' ',st)+1) AS SIGNED);
+----+------+
| id | st   |
+----+------+
|  1 | a 1  |
|  5 | b 1  |
|  3 | a 6  |
|  7 | b 6  |
|  4 | a 11 |
|  8 | b 11 |
|  2 | a 12 |
|  6 | b 12 |
+----+------+
8 rows in set (0.00 sec)

mysql> SELECT * FROM t ORDER BY LEFT(st,LOCATE(' ',st)), CAST(SUBSTRING(st,LOCATE(' ',st)+1) AS SIGNED);
+----+------+
| id | st   |
+----+------+
|  1 | a 1  |
|  3 | a 6  |
|  4 | a 11 |
|  2 | a 12 |
|  5 | b 1  |
|  7 | b 6  |
|  8 | b 11 |
|  6 | b 12 |
+----+------+
8 rows in set (0.00 sec)

ignore my lame table/column names, but gives me the correct result. Also went a little further and added double sort to break letters prefix with numeric.

Edit SUBSTRING_INDEX will make it little more readable.

ORDER BY SUBSTRING_INDEX(st, " ", 1) ASC, CAST(SUBSTRING_INDEX(st, " ", -1) AS SIGNED)

Solution 2:

You can try this:

ORDER BY CASE
  WHEN ISNUMERIC(column) THEN cast(column as int) 
  else ascii(column[1,1]) 
end

Solution 3:

Have a look at the MySQL CAST / Convert functions.

SELECT name FROM mytable ORDER BY CAST(name AS INTEGER) ASC;

Edit: I read:

I am trying to sort string column (containing numbers).

...but just took a look at the result set. Is the a actually also part of the contents? If so, you can use functions like MID to extract only the numeric value and cast that.

But if all rows contain just a without variation, you might as well omit it...