Learn the
fundamentals in our short video tutorial which shows you how
to write a program in PL/SQL to display "Hello World" in about 30
seconds!
PL/SQL is
Oracle's proprietary, block-structured,
strongly-typed, procedural programming language for manipulating data
and interacting with Oracle databases.
The procedural part is important. PL/SQL provides
you with all the things that SQL lacks like user-defined functions,
loops, control statements (though SQL does provide some control in the
form of the CASE clause, and the DECODE and NVL functions.). In fact
the name stands for "Procedural Language extensions to the Structured
Query Language".
Overall PL/SQL is a high-level language very
similar to Pascal and ADA (from which it is derived). As Pascal was
designed as a teaching language, this makes PL/SQL easy to learn and to
use and it promotes good programming practice. Although it is still
possible to write bad code using PL/SQL, you just have to try that bit
harder to do so!
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PL/SQL has been described as the poor man's
object-oriented language, but that was harsh even before the specific
object-oriented features were added in Oracle8. PL/SQL is a very
powerful and flexible language which, whilst not strictly
object-oriented like Java, still has some o-o features, such as
encapsulation, data hiding, inheritance, object types etc.
However, not all object-oriented features are
available in all versions of PL/SQL The higher the version you're
using, the more o-o features are available. Coverage of the
object-oriented features has been deferred to a separate PL/SQL
tutorial.
What can PL/SQL do?
Or, perhaps more importantly, what can you do with
PL/SQL? The answer is plenty.
As hinted at earlier, you can define your own
functions which can be embedded in SQL statements in the same way as
the built-in functions.
You can also use it to write complete programs to
implement business logic, furthermore you can store these programs in
the database itself (and take advantage of the extra power of the
server) or in Oracle Forms and Reports.
Stored procedures can be invoked from SQL, or
other languages such as Java, C, FORTRAN or Visual Basic.
Unfortunately, all of these topics are outside the scope of this PLSQL
tutorial.
In short there is little that you can't do - as
long as you don't need fancy i/o or file handling features. The only
language element for displaying information directly to the end-user is
the DBMS_OUTPUT package, whilst the (limited) file handling
capabilities are provided by the UTL_FILE package.
That was just a brief overview of the
language
- this tutorial continues with
