It is the same difference between an OR Boolean and AND Boolean. In an OR query, you are looking for something that matches one of several possible values, while in an AND query, you are looking for...
QL is an object-oriented query language used to retrieve data from relational database management systems. It is reminiscent of the standard query language SQL and the object-oriented programming...
Select queries do not change the data. They will show lists of data and various statistics and other requirements. Action queries do things like update records or delete records, which is changing...