sql injection related to iSeries

After reviewing archives, I see warnings about sql injection affecting all sql 
processing databases, but all the examples I've found so far on web cover 
ms sql specific problems. Assuming the iSeries does not recognize the  --
problem, and if I either strip single quotes out of user input, or add the 
proper 
extra single quote (BJ'S  =  BJ''S),  what would be a good 
practice to code wherever sql is processed? 
As an example, if I have a screen where user can search by name, and 
user enters JOHN, my sqlrpgle builds a string like  
select * from xyz where wwname like '%JOHN%'
What syntax could someone enter to mess with the system?
Jim Franz