? parameter in mysql query

hazno · #1 (**permalink**) 04-21-2009

I am debugging some code and came across ? in the WHERE cause in a mysql query.

Is this possible and what situations would this be used?

Code:

SELECT ip, count
FROM  table
WHERE domain=?

thanks & regards

amitranjansahu · #2 (**permalink**) 04-21-2009

yOU CAN USE THE FOLLOWING . iS IT WHAT U WANT ?

SELECT IP,COUNT FROM TABLE where DOMAIN LIKE '%%' ;

cbkihong · #3 (**permalink**) 04-21-2009

? is a parameter placeholder. That way you don't have to directly compose the SQL with parameters given (failure to escape the parameters properly is the major reason for SQL injection attacks).

Typically, the ? is not valid at the database layer. Normally the database library will dynamically replace them with the parameters (converting where necessary) in the SQL and pass the resulting the query to the database. In other cases, the database engine may accept placeholders itself, especially true if the db supports prepared statements so that an SQL can be prepared once, thus allowing it to be instantiated multiple times to perform the same query with different set of parameters.

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