دانلود کتاب یادگیری SQL – تولید، دستکاری و بازیابی داده ها

Programming languages come and go constantly, and very few languages in use today have roots going back more than a decade or so. Some examples are Cobol, which is still used quite heavily in mainframe environments, and C, which is still quite popular for operating system and server development and for embedded systems. In the database arena, we have SQL, whose roots go all the way back to the 1970s. SQL is the language for generating, manipulating, and retrieving data from a relational database. One of the reasons for the popularity of relational databases is that properly designed relational databases can handle huge amounts of data. When working with large data sets, SQL is akin to one of those snazzy digital cameras with the highpower zoom lens in that you can use SQL to look at large sets of data, or you can zoom in on individual rows (or anywhere in between). Other database management systems tend to break down under heavy loads because their focus is too narrow (the zoom lens is stuck on maximum), which is why attempts to dethrone relational databases and SQL have largely failed. Therefore, even though SQL is an old language, it is going to be around for a lot longer and has a bright future in store.