Using single quote vs back tic

potatoCode

What is the difference between using single quote and back quote?

SELECT * FROM [b]`[/b]db`.'table'

SELECT * FROM [b]'[/b]db'.'table'

MySQL Query Broswer (and others) uses back tic while some others use single quotes.
Can anyone clear this up?

Thanks.

Bjom

some others definitely do not use single quotes - it might only look like it.

Backtick is to identify userdefined names like for fields and tables.

Single quotes identify strings.

So:

...SET `myField` = 'someStringValue'...;

but never ....SET 'myField' = someStringValue....;

Another note: The backticks are optional while the single quotes are not. The backticks make sure however that your "names" are always identified as such even when they collide with SQL keywords.

Example "age" in German is "Alter". Unfortunately "alter" is also a SQL keyword.

So this would fail:

SELECT age as Alter ....

while this would not:

 SELECT `age` as `Alter`...

Bjom

Weedpacket

Single quotes are used to delimit string literals. Backticks are MySQL's nonstandard way of escaping table and column names that match SQL keywords (the standard is to use double quotes, though some use square brackets).

potatoCode

Thanks for the reply Bjom, eedpacket.

My understanding(or should I say confusion?) about the backticks was that,
according to the reference material, it excutes the enclosed string as the shell command in PHP.
Then I saw it used in SQL Query Broswer, so I got confused.
Thanks for clearing that up.

Weedpacket

PHP is not MySQL; and vice versa.