Karen...

Despite Firebird's small footprint, it is nonetheless an enterprise database engine, which can go toe-to-toe with any of the popular database engines on the market currently in terms of single server installations or small server clusters right "out of the box".  For heavy duty, large scale requirements, there is an enhanced version of Firebird, which available for organizations that require such power.

That being said, Firebird is not a database engine I would recommend to a person who is just starting to learn how to handle database engines.

All such engines use SQL in one variant or the other, in line with the latest standards available. 

I would suggest then that you consider picking up the O'reilly book, "Learning SQL - 2nd Edition", which would be an excellent aid in helping you learn SQL in general.  Here is the US Amazon link... https://www.amazon.com/Learning-SQL-Master-Fundamentals/dp/0596520832/ref=sr_1_3?s=books&ie=UTF8&qid=1535051590&sr=1-3&keywords=learning+sql

A recommended database manager is a tool called, "DBeaver", which offers free versions for Windows, Linux, and Mac systems, and can be obtained at this link...  https://dbeaver.io/

Using ISQL to learn how to handle a database engine is a fairly difficult thing to do since you cannot easily test out the more complex types of queries you may want to experiment with.  And it is not very helpful when you run into issues.

From the way you wrote your initial notes on this forum it sounded as if you are using Firebird in a local setting.  If that is true, you may want to consider using the Embedded version instead of the server version as there is somewhat less complexity involved in making connections to it.  However, if your current installation is sound, leave it alone then.

As I mentioned earlier, you should get a hold of the Firebird 2.5 Language reference manual from the Firebird web site.  Though version 3.x is now available, I don't believe the language reference documentation has been completed for this latest version.  Nonetheless, the 2.5 manual will answer practically every SQL language question you may have for Firebird SQL.  Get a copy of it printed out from your local print shop and keep it by your side as you are learning Firebird.

Remember that learning SQL in general prepares you to handle most situations you will come across. However, each SQL variant can do the same things but with their own twists based on the database engines they are for.  Firebird SQL is no different.

The book I suggested shows variations for SQL used with SQL Server, Oracle, and MySQL  For your purposes, stick with the SQL Server and MySQL variants (Oracle can be overly complex) and then try to transpose your knowledge to the Firebird Engine.

To afford you assistance more easily, please let me know how you have the Firebird Engine set up for your learning experience.

If you need additional help with a server-based implementation, I will install Firebird 3,x on my own server so I can better understand the issues you are running into.  Right now I am using the Embedded edition for the type of development efforts I am working on...

Steve Naidamast

Sr. Software Engineer