3.16 Sorting a Result Set
3.16.1 Problem
Your query results
aren't sorted the way you want.
3.16.2 Solution
MySQL can't read your mind. Add an
ORDER BY clause to tell it
exactly how you want things sorted.
3.16.3 Discussion
When you select rows, the MySQL server is free to return them in any
order, unless you instruct it otherwise by saying how to sort the
result. There are lots of ways to use sorting techniques. Chapter 6 explores this topic further. Briefly, you sort
a result set by adding an ORDER
BY clause that names the column or columns you
want to sort by:
mysql> SELECT * FROM mail WHERE size > 100000 ORDER BY size;
+---------------------+---------+---------+---------+---------+---------+
| t | srcuser | srchost | dstuser | dsthost | size |
+---------------------+---------+---------+---------+---------+---------+
| 2001-05-12 12:48:13 | tricia | mars | gene | venus | 194925 |
| 2001-05-15 10:25:52 | gene | mars | tricia | saturn | 998532 |
| 2001-05-14 17:03:01 | tricia | saturn | phil | venus | 2394482 |
+---------------------+---------+---------+---------+---------+---------+
mysql> SELECT * FROM mail WHERE dstuser = 'tricia'
-> ORDER BY srchost, srcuser;
+---------------------+---------+---------+---------+---------+--------+
| t | srcuser | srchost | dstuser | dsthost | size |
+---------------------+---------+---------+---------+---------+--------+
| 2001-05-15 10:25:52 | gene | mars | tricia | saturn | 998532 |
| 2001-05-14 11:52:17 | phil | mars | tricia | saturn | 5781 |
| 2001-05-17 12:49:23 | phil | mars | tricia | saturn | 873 |
| 2001-05-11 10:15:08 | barb | saturn | tricia | mars | 58274 |
| 2001-05-13 13:59:18 | barb | saturn | tricia | venus | 271 |
+---------------------+---------+---------+---------+---------+--------+
To sort a column in reverse (descending) order, add the keyword
DESC after its name in the
ORDER BY clause:
mysql> SELECT * FROM mail WHERE size > 50000 ORDER BY size DESC;
+---------------------+---------+---------+---------+---------+---------+
| t | srcuser | srchost | dstuser | dsthost | size |
+---------------------+---------+---------+---------+---------+---------+
| 2001-05-14 17:03:01 | tricia | saturn | phil | venus | 2394482 |
| 2001-05-15 10:25:52 | gene | mars | tricia | saturn | 998532 |
| 2001-05-12 12:48:13 | tricia | mars | gene | venus | 194925 |
| 2001-05-14 14:42:21 | barb | venus | barb | venus | 98151 |
| 2001-05-11 10:15:08 | barb | saturn | tricia | mars | 58274 |
+---------------------+---------+---------+---------+---------+---------+
|
