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I'm not quite sure stackoverflow is a place for such a general question, but let's give it a try.
Being exposed to the need of storing application data somewhere, I've always used MySQL or sqlite, just because it's always done like that. As it seems like the whole world is using these databases (most of all software products, frameworks, etc), it is rather hard for a beginning developer like me to start thinking about whether this is a good solution or not.
Ok, say we have some object-oriented logic in our application, and objects are related to each other somehow. We need to map this logic to the storage logic, so relations between database objects are required too. This leads us to using relational database, and I'm ok with that - to put it simple, our database table rows sometimes will need to have references to other tables' rows. But why use SQL language for interaction with such a database?
SQL query is a text message. I can understand this is cool for actually understanding what it does, but isn't it silly to use text table and column names for a part of application that no one ever seen after deploynment? If you had to write a data storage from scratch, you would have never used this kind of solution. Personally, I would have used some 'compiled db query' bytecode, that would be assembled once inside a client application and passed to the database. And it surely would name tables and colons by id numbers, not ascii-strings. In the case of changes in table structure those byte queries could be recompiled according to new db schema, stored in XML or something like that.
What are the problems of my idea? Is there any reason for me not to write it myself and to use SQL database instead?
EDIT To make my question more clear. Most of answers claim that SQL, being a text query, helps developers better understand the query itself and debug it more easily. Personally, I haven't seen people writing SQL queries by hand for a while. Everyone I know, including me, is using ORM. This situation, in which we build up a new level of abstraction to hide SQL, leads to thinking if we need SQL or not. I would be very grateful if you could give some examples in which SQL is used without ORM purposely, and why.
EDIT2 SQL is an interface between a human and a database. The question is why do we have to use it for application/database interaction? I still ask for examples of human beings writing/debugging SQL.
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We strongly recommend that you always close the connection when you are finished using it so that the connection will be returned to the pool.
If you don't close the database connections, they'll cause memory leaks over time. The Notepad example does use startManagingCursor , but you still need to explicitly close the db connection.
Once you are done using the database, you must close it. You use the DB->close() method to do this. Closing a database causes it to become unusable until it is opened again.
If you don't close it, it leaks, and ties up server resources. @EJP The connection itself might be thread-safe (required by JDBC), but the applications use of the connection is probably not threadsafe. Think of things like different transaction isolation, boundaries (commit/rollback/autocommit) etc.
Everyone I know, including me, is using ORM
Strange. Everyone I know, including me, still writes most of the SQL by hand. You typically end up with tighter, more high performance queries than you do with a generated solution. And, depending on your industry and application, this speed does matter. Sometimes a lot. yeah, I'll sometimes use LINQ for a quick-n-dirty where I don't really care what the resulting SQL looks like, but thus far nothing automated beats hand-tuned SQL for when performance against a large database in a high-load environment really matters.
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