Often you might be in situations where you want to query your mysql database with multiple AND and OR statements in the WHERE clause., which is why i use brackets to nest either OR and AND statments. Those conditions within the brackets will be executed first in the mysql query.
Lets say for example,
SELECT * from `pricelist` where cost > 10 and color=’red’ or weight > 100
The best way to write above query is
SELECT * from `pricelist` where cost > 10 and (color=’red’ or weight > 100)
Notice from above sql statement we have used 3 conditions in the WHERE clause. Notice that our main criteria is to pick up results having cost greater than $10. This is because the condition statement within brackets get precedence and executed first.
It is always
Note: Often NOT using brackets will lead to mystery results produced by mysql.
