Recipe 3.11. Sorting a Result Set
ProblemYour query results aren't sorted the way you want. SolutionMySQL can't read your mind. Add an ORDER BY clause to tell it exactly how you want result rows sorted. DiscussionWhen 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 7 explores this topic in detail. Briefly, you sort a result set by adding an ORDER BY clause that names the column or columns that you want to use for sorting. The following statement sorts rows by size: mysql> SELECT * FROM mail WHERE size > 100000 ORDER BY size; +---------------------+---------+---------+---------+---------+---------+ | t | srcuser | srchost | dstuser | dsthost | size | +---------------------+---------+---------+---------+---------+---------+ | 2006-05-12 12:48:13 | tricia | mars | gene | venus | 194925 | | 2006-05-15 10:25:52 | gene | mars | tricia | saturn | 998532 | | 2006-05-14 17:03:01 | tricia | saturn | phil | venus | 2394482 | +---------------------+---------+---------+---------+---------+---------+ This statement names multiple columns in the ORDER BY clause to sort rows by host, and then by user within each host: mysql> SELECT * FROM mail WHERE dstuser = 'tricia' -> ORDER BY srchost, srcuser; +---------------------+---------+---------+---------+---------+--------+ | t | srcuser | srchost | dstuser | dsthost | size | +---------------------+---------+---------+---------+---------+--------+ | 2006-05-15 10:25:52 | gene | mars | tricia | saturn | 998532 | | 2006-05-14 11:52:17 | phil | mars | tricia | saturn | 5781 | | 2006-05-17 12:49:23 | phil | mars | tricia | saturn | 873 | | 2006-05-11 10:15:08 | barb | saturn | tricia | mars | 58274 | | 2006-05-13 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 | +---------------------+---------+---------+---------+---------+---------+ | 2006-05-14 17:03:01 | tricia | saturn | phil | venus | 2394482 | | 2006-05-15 10:25:52 | gene | mars | tricia | saturn | 998532 | | 2006-05-12 12:48:13 | tricia | mars | gene | venus | 194925 | | 2006-05-14 14:42:21 | barb | venus | barb | venus | 98151 | | 2006-05-11 10:15:08 | barb | saturn | tricia | mars | 58274 | +---------------------+---------+---------+---------+---------+---------+ |
