Question

I have heard some strong developers say that “inline SQL in and of itself is not evil”. I do not understand how inline SQL is acceptable. To me its just like hard coding. Many a developer would scoff in my face for putting a connection string in the code vs a config file. So why is it that “SELECT value1,value2 FROM TABLE” is perfectly acceptable in compiled code?

Answer 1

I think there is a lot of coupling between a database query and the code that surrounds it. For example, a query might fetch first name and last name for a particular user from a database, and then create an XML file containing the first name and last name.

If you put the database query somewhere else (e.g. config file) it might seem like you’ve increased configurability and flexibility. However, if you want to actually change it, say add a field called “age” to the XML file, you can’t just change the query alone, you need to change the code writing the XML file. So in fact you’ve replaced the problem of having to change one piece of code, with the problem of having to change two things (code and configuration), and the danger that they might not be consistent, and you haven’t gained any extra flexibility.

(If it seems like one can just write generic code to take all database fields and put them in the XML file, consider the case where age is stored as the birth year in the database, and you have to do computation to create the age.)