MySQL/PHP Query

Answer 1

Never use concatenation to generate your SQL, you should be using prepared SQL statements with parameters.

The only way to simplify this statement without having greater knowledge of the problem domain is to reduce the number of columns. It looks as if you've got three prices per product entry. You could create a table of product prices instead of columns of product prices and this would make it a single comparison and give you the flexibility to create yet more product prices in the future.

So you'll need to create a one->many relationship between product and prices.

Answer 2

Okay so what is your question?

Answer 3

Performance improvement: Your query is OR based, meaning that it will stop evaluating the conditions as soon as it finds one of them being true. Try to order your conditions in such a way that, for example, in your case, the first check is the most likely to be under 400.

Security imporvement: Use prepared statements and filter out your variables before using them. In case of the $ObrKursQuery, if it comes from a user input or an untrusted source, this is a non-quoted numeric value and you are exposed to a big variety of sql injection problems (including arithmetic sql injection: if that value is 0, you'll get a divideByZero error that can be used as a blind sql injection condition).

Readability imporvement: Be sure to always be consistent in the way you write your code, and if possible, follow some accepted de facto standard, like starting variable names lower case: $ObrKursQuery -> $obrKursQuery. Also for the sake of self documenting code, choose names for your variables that mean what they are: $ObrKursQuery -> $conversionRatio.

Maintainability/Scalability improvement: Use a constant instead of a fixed value for the 400. When you change that value in the future, you will want to change it in just one place and not all over your code.