What are these SQL words?

I know standard SQL such as ORACLE.

I often see keywords like these that developers have in their code.  It seems like something on top of SQL.  I don't know what they are.  I'd be happy to know what they are and then I can read about the topic.  If someone had time,  I'd like to know what they are:

AFTER
FOR
WHEN
BEGIN
REFERENCING
CAST

I wish there was a Forum choice of Database SQL newbie.   My question is not advanced enough to fit into any existing drop down category.

Thaniks,

Kevin

Most of the database vendors extend standard SQL(*) with extra functionality.  
Oracle has PL/SQL which is a cursor-based language - in simplistic terms this allows you to create "loops".

They always have good documentation (and lots of it!) -PL/SQL Language Elements

(*) if there is a standard!  

Peter,

I remembered it being part of SQL but I wasn't sure if I needed to use an add on of some kind.  Now I know it is part of Oracle or probably also built into other SQLs.

I can now look in the Oracle documentation to learn what each one does.

Thanks,

Kevin

Peter,

I went to the link and I see a lot of information about PL1 but not the simple looking words I mentioned.  I'm wondering if they are something else.  It looks like PL / ORACLE but I don't know why the keywords are not in the documentation.

Kevin

Some of these words are part of longer PL/SQL commands,After Update and For loop

@Peter...Appreciated

kevin Abel wrote:Peter,

I went to the link and I see a lot of information about PL1 but not the simple looking words I mentioned.  I'm wondering if they are something else.  It looks like PL / ORACLE but I don't know why the keywords are not in the documentation.

Kevin

PL1, also known as PL/1, PL/I, Programming Language/1*, was a language developed by IBM in the later 1960s (I think). It was an attempt to create a "universal" language for their mainframe computers. Prior to that, languages tended to be more specialized: Fortran for scientific computing, COBOL for business computing. PL/1 syntax was more like the formulaic Fortran than the verbose COBOL, but it supported some of the hardware data types that COBOL allowed but Fortran did not (for example, BCD-style arithmetic). It was one of the first major languages to adapt to the new-fangled "structured programming" model that became an essential part of OOP.

It wasn't as popular as Fortran and COBOL (both of which were available for free from IBM, where PL/1 was not), but it did see some commercial use. I worked with it at my first computer job, in fact. It had an optimising compiler (extra-cost) product back when most compilers were non-optimising.

Fred Brooks held it up as a systems programming language in his seminal book The Mythical Man-Month and IBM did, in fact develop a dialect of it called PL/S that was used to write much of the IBM OS/VS operating system code. PL/S was closer to the hardware (vanilla PL/1 code couldn't operate in the specialised internal environment of an operating system). And, alas, for those of us doing OS-level coding outside of IBM, they wouldn't share it. We spent literally years trying to find a suitable equivalent.

As a side note, the Prime Computer company (perhaps best noted for using Dr. Who as a spokesman) had originally designed their hardware to optimally run Fortran, but Fortran has certain limitations such as not being originally designed as a structured programming language nor easily adaptable to that paradigm, so in the 1980s, Prime adapted a dialect of PL/1 to be the new systems  programming language for their OS products. Unlike IBM, they made it available for free to customers.

PL/1 syntax was almost certainly influenced by Algol, though Algol was never very popular in the USA. And from thence we get C and finally Java.

SQL does have primitive a PL/1-like syntax. which wouldn't be surprising since SQL has roots at IBM and IBM has a fairly consistent model for all of the language-like products that they produce such as OS system utilities.

However, having said all that. PL/1 is not PL/SQL nor SQL and any overlaps in keywords between them are purely incidental.

---
* IBM apparently liked the name so much that they also copyrighted PL/2 through PL/99 for future use.

PL/SQL is a procedural extension of SQL. It runs inside the Oracle Database products and was created in the early nineties.
With PL/SQL, you can write procedures that are stored in the database.
Such procedures can be included in packages (similar to Java packages).
Another big benefit of PL/SQL is strong exception handling.
SQL can be embedded in PL/SQL, though there are reasons for not doing this (excessively).

was a language developed by IBM

Oh, I never knew that.  Way back I was developing using Informix 4GL/SQL.  Back then Informix were the major rivals to Oracle Highway 101 Billboard and eventually lost out.