Comments on: Less known SQL syntax and functions in MySQL http://code.openark.org/blog/mysql/less-known-sql-syntax-and-functions-in-mysql Blog by Shlomi Noach Wed, 01 Feb 2012 20:47:51 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Discovery of the day: GROUP BY DESC | code.openark.org http://code.openark.org/blog/mysql/less-known-sql-syntax-and-functions-in-mysql/comment-page-1#comment-13077 Discovery of the day: GROUP BY DESC | code.openark.org Tue, 04 May 2010 09:38:44 +0000 http://code.openark.org/blog/?p=126#comment-13077 [...] are sorted according to the group statement. You can override this by adding ORDER BY NULL (see past post). I wasn’t aware you can actually control the sort [...] [...] are sorted according to the group statement. You can override this by adding ORDER BY NULL (see past post). I wasn’t aware you can actually control the sort [...]

]]> By: shlomi http://code.openark.org/blog/mysql/less-known-sql-syntax-and-functions-in-mysql/comment-page-1#comment-9573 shlomi Wed, 20 Jan 2010 06:56:31 +0000 http://code.openark.org/blog/?p=126#comment-9573 @Tim, There's some contradiction in your comment, I think. AFAIK, there is no LIMIT in ANSI SQL. Therefore, it is purely a MySQL extension. Thus, there is no "standard SQL way" for doing LIMIT. Using one syntax over the other is a matter of preference and, in my case, and old habit. I agree using LIMIT with OFFSET is more verbose. Regards @Tim,

There's some contradiction in your comment, I think. AFAIK, there is no LIMIT in ANSI SQL. Therefore, it is purely a MySQL extension. Thus, there is no "standard SQL way" for doing LIMIT.

Using one syntax over the other is a matter of preference and, in my case, and old habit. I agree using LIMIT with OFFSET is more verbose.

Regards

]]> By: Tim http://code.openark.org/blog/mysql/less-known-sql-syntax-and-functions-in-mysql/comment-page-1#comment-9548 Tim Tue, 19 Jan 2010 19:24:05 +0000 http://code.openark.org/blog/?p=126#comment-9548 Your Oracle DBA was shocked that you're using "LIMIT" for pagination because that syntax is a MySQL extension. The standard SQL way would be "LIMIT 10 OFFSET 60". MySQL also supports OFFSET, and it makes it clearer which number is which, so I'm not sure why you'd ever use "LIMIT a,b". Your Oracle DBA was shocked that you're using "LIMIT" for pagination because that syntax is a MySQL extension. The standard SQL way would be "LIMIT 10 OFFSET 60".

MySQL also supports OFFSET, and it makes it clearer which number is which, so I'm not sure why you'd ever use "LIMIT a,b".

]]> By: Kannan http://code.openark.org/blog/mysql/less-known-sql-syntax-and-functions-in-mysql/comment-page-1#comment-165 Kannan Fri, 19 Dec 2008 06:35:32 +0000 http://code.openark.org/blog/?p=126#comment-165 Good Post for MySQL. Good Post for MySQL.

]]> By: shlomi http://code.openark.org/blog/mysql/less-known-sql-syntax-and-functions-in-mysql/comment-page-1#comment-123 shlomi Wed, 17 Dec 2008 05:25:35 +0000 http://code.openark.org/blog/?p=126#comment-123 Hi Jason, I've seen a very bad effect of REPLACE INTO in a production system. The overhead of DELETEing a row, then INSERTing a new one is huge, especially on InnoDB tables. Changing the code to INSERT INTO...ON DUPLICATE KEY reduced the load average on the db machine by factors. Hi Jason,

I've seen a very bad effect of REPLACE INTO in a production system. The overhead of DELETEing a row, then INSERTing a new one is huge, especially on InnoDB tables. Changing the code to INSERT INTO...ON DUPLICATE KEY reduced the load average on the db machine by factors.

]]> By: Jason http://code.openark.org/blog/mysql/less-known-sql-syntax-and-functions-in-mysql/comment-page-1#comment-120 Jason Wed, 17 Dec 2008 02:14:38 +0000 http://code.openark.org/blog/?p=126#comment-120 I personally like the REPLACE INTO command... same syntax as INSERT INTO, except if it finds a duplicate key, it deletes it and replaces it.... Similar in spirit to the UPDATE... ON DUPLICATE KEY UPDATE, the difference being - REPLACE INTO will delete and then insert so you get incremented auto numbered IDs I personally like the REPLACE INTO command... same syntax as INSERT INTO, except if it finds a duplicate key, it deletes it and replaces it....

Similar in spirit to the UPDATE... ON DUPLICATE KEY UPDATE, the difference being - REPLACE INTO will delete and then insert so you get incremented auto numbered IDs

]]> By: A day in the life of… - Once a nomad, always a nomad http://code.openark.org/blog/mysql/less-known-sql-syntax-and-functions-in-mysql/comment-page-1#comment-62 A day in the life of… - Once a nomad, always a nomad Tue, 02 Dec 2008 23:01:17 +0000 http://code.openark.org/blog/?p=126#comment-62 [...] Bookmarked a link on Delicious. Less known SQL syntax and functions in MySQL | code.openark.org [...] [...] Bookmarked a link on Delicious. Less known SQL syntax and functions in MySQL | code.openark.org [...]

]]> By: rudy http://code.openark.org/blog/mysql/less-known-sql-syntax-and-functions-in-mysql/comment-page-1#comment-47 rudy Wed, 26 Nov 2008 01:04:03 +0000 http://code.openark.org/blog/?p=126#comment-47 there is another feature (some would not use this word) in mysql that is stunning in its implication -- "hidden" columns in the GROUP BY at first, i thought it was an egregious error that mysql would allow a query like this: SELECT a, b, MAX(c) FROM t GROUP BY a most databases toss an error about column b in the SELECT clause but not in the GROUP BY read this article, which completely changed my mind on the issue -- http://rpbouman.blogspot.com/2007/05/debunking-group-by-myths.html (also republished on mysql.com) keep "functional dependency" in mind (from normalization theory) and see if you don't agree that it can be exceptionally useful there is another feature (some would not use this word) in mysql that is stunning in its implication -- "hidden" columns in the GROUP BY

at first, i thought it was an egregious error that mysql would allow a query like this:

SELECT a, b, MAX(c) FROM t GROUP BY a

most databases toss an error about column b in the SELECT clause but not in the GROUP BY

read this article, which completely changed my mind on the issue -- http://rpbouman.blogspot.com/2007/05/debunking-group-by-myths.html (also republished on mysql.com)

keep "functional dependency" in mind (from normalization theory) and see if you don't agree that it can be exceptionally useful

]]> By: shlomi http://code.openark.org/blog/mysql/less-known-sql-syntax-and-functions-in-mysql/comment-page-1#comment-46 shlomi Tue, 25 Nov 2008 14:12:05 +0000 http://code.openark.org/blog/?p=126#comment-46 Hi Nils, CLUSTER in PostgreSQL seems to only work on an index, while ALTER TABLE...ORDER BY will work on any columns. Hi Nils,
CLUSTER in PostgreSQL seems to only work on an index, while
ALTER TABLE...ORDER BY will work on any columns.

]]> By: Nils http://code.openark.org/blog/mysql/less-known-sql-syntax-and-functions-in-mysql/comment-page-1#comment-45 Nils Tue, 25 Nov 2008 12:55:57 +0000 http://code.openark.org/blog/?p=126#comment-45 The ALTER TABLE ... ORDER BY thing is similar to CLUSTER in postgres I think. http://www.postgresql.org/docs/8.3/interactive/sql-cluster.html The ALTER TABLE ... ORDER BY thing is similar to CLUSTER in postgres I think.

http://www.postgresql.org/docs/8.3/interactive/sql-cluster.html

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