On 09-Apr-2012 12:34 , Nathan Andelin wrote:
RPG Code:


SQL injection can be fun ;-) What if the value for the char(10) variables ytmlink.district and ytmlink.school [as presumed input from a user] are the following [non-delimited by quotation marks] string?:
"'or 1='1 "

If accepted as input, then the expression:
filter = 'DISTRICT = ' + squote + ytmlink.district + squote +
' AND SCHOOL = ' + squote + ytmlink.school + squote;

Evaluates to the string:
DISTRICT = ''or 1='1 ' AND SCHOOL = ''or 1='1 '

Even if the application avoids injection by some means of validity checking the input, the SQL as coded is not very reusable if\when stored in the cache "as is", because the values are literals instead of parameter markers. The SQL is made safe from injection, more directly enabled capable for reuse, and IMO much more readable when constructed as a string when using instead the expression:
filter = 'DISTRICT = ? AND SCHOOL = ?';

Regards, Chuck

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