The previous chapter explored the subject of SQL in detail, so you should now have a good understanding of how to add data to a database, how to remove it, how to modify it and, perhaps most importantly, how to find and retrieve the particular data you want, structured in a way best suited to your needs.
SQL is only one part of the story. The relational model may appear abstract and SQL more concrete, but SQL itself is only a language. Just as communicating successfully with people involves far more than simply knowing the right language, efficient database programming requires more than knowledge of SQL alone.
This chapter introduces a number of important concepts, all of which are essential for proficient database programming. Once you've read and understood this chapter, you'll be ready to move on to Chapter 6, which describes the Symbian SQL APIs.
The chapter starts by describing the different types of database supported by Symbian SQL. Then I look at the mechanisms Symbian SQL provides to execute SQL on such databases. Finally, I move on to look at multi-client access, in particular focusing on the locking model implemented in Symbian SQL.
A Symbian SQL database is contained within a single file – and a file can contain only one database. This convenient fact means that new databases may be brought to the device by simply copying the database file to the correct location in the file system. Existing databases are just as easily backed ...