What does "#" signify in MySql?

Question

I come from a SQL Server background and thought that it might mean it was a temporary table, but after reading up on MySql temp tables I don't think that's true.

I'm seeing it in the following context:

SELECT ID, Name FROM #_SomeName

UPDATE

This query is defined in a PHP string and then run against the MySQL Database. I'm not sure if that would make a difference or not...

here is the PHP code i'm running:

$query="select id, name from #__SomeName"; $db=&JFactory::getDBO(); $db->setQuery($query);

Where did you get this code from? I'm not sure what JFactory is, but could it be that the setQuery method actually modifies the query before sending it to MySQL? — casablanca
– casablanca, Commented Jul 2, 2010 at 17:02

Mike · Accepted Answer · 2010-07-02 17:04:09Z

5

In MySQL # is an end-of-line comment:

http://dev.mysql.com/doc/refman/5.1/en/comments.html

In JFactory, #__ is used as a place holder. See here:

http://docs.joomla.org/How_to_use_the_database_classes_in_your_script

edited Jul 2, 2010 at 17:04

answered Jul 2, 2010 at 16:53

Mike

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1 Comment

Abe Miessler Over a year ago

Ahh thanks, sorry for the confusion. As you can tell i'm not that familiar with joomla, php, mysql etc.

Jason McCreary · Accepted Answer · 2010-07-02 16:50:22Z

2

A Comment

# comment -- also a comment

The syntax highlighting answers the question ;)

answered Jul 2, 2010 at 16:50

Jason McCreary

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Comments

just somebody · Accepted Answer · 2010-07-02 16:59:19Z

are you sure the table name is not quoted using backticks? maybe in the issuing application? it might show up in MySQL's query log bare.

mysql> create table `#t` (i int); mysql> insert into `#t` (i) values (10); mysql> select * from `#t`; +------+ | i | +------+ | 10 | +------+

MBCook · Accepted Answer · 2010-07-02 16:53:05Z

It's usually a comment character. Are there more lines to your script? Basically, I'd expect something like this:

SELECT id, name, whatever FROM #_table my_table WHERE id = 7;

Maybe someone commented out the old table name and put a new one in?

Hmm very strange. No there are no more lines. So this is actually a string defined in a PHP page that is then run against a MySQL DB, could that make a difference?

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