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In general SQL concept will be same across all RDBMS, the only different is how you write the query just like programming, in general the concept is the same, the language use will make it different from one to another.
For Relational Database Management System, SQL is just like same for all applications where as still there are few differences in SQL functions like "Decode", etc.
If you know and used SQL on any platform, it will be easy to work on all others which are mentioned in your question.
SQL is Simply a Structure query language , in an other simple way we can say SQL is the way of how to write the query for collecting, maniuplating , or even deleting or updating some data from your database platform , your database might be ACCESS , SQL , Oracle , etc...
But you should notice that all ACCESS + SQL SERVER + Oracle can be Considered as RDBMS which stand for relational Database Management System , in another word all of ( ACCESS , SQL , Oracle ) are some how a way of Storing some related information or data all together but when you want to collect , or choose or say update or manipulate some data or information stored in your RDBMS then you should fire the query language which is the SQL language ..
SQL stand for Structure Query Language.SQL is a standard language for accessing databases. It was developed by IBM. But RDBMS vendors SQL syntax use with their product and they add some additional programming features that is different from each vendors.
Like In SQL server T-SQL
Oracle PL/SQL
the deference about how the database engine implementing data and retrieve it , how many user can use it at same time , but if we have additional options in one of them it must have some deference to use it
Some syntax is same , but in PL-SQL you will find the difference between language vendors
Most of the rdbms (MS SQL Server, Oracle, DB2, Postgre SQL, MySQL) implementation of SQL is conformed to SQL-92 and recent ones.
Meaning that the basis is the same.
BUT There are differencies, linked to the engine that is used by the rdbms:
In Microsoft SQL Server, they call it T-SQL, Transact SQL.
For example,
---- All types of join are not supported by all rdbms (Natural joins, using clause, ...)
---- The consequences of a statement is not the same in those rdbms
---- Create table Table_name as select * from view_name ; is not allowed in Postgre SQL whereas it works perfectly for Others (MySQL, DB2, Oracle, ...)
---- Nulls last and first is not available in MySQL
---- .......
There is a lot of differencies!!!!!!
first SQL is not language it is more like (Structured Query Language)
second, the answer for your question is yes and no, SQL implementations are incompatible between vendors and do not necessarily completely follow standards. In particular date and time syntax, string concatenation, NULLs, and comparison case sensitivity vary from vendor to vendor.
but the National Institute of Standards and Technology (NIST) data management standards program certified SQL DBMS compliance with the SQL standard. Vendors now self-certify the compliance of their products and through the years we start to see standards like: SQL-86, SQL-87, SQL-89, SQL-92, SQL:1999, SQL:2003, SQL:2006, SQL:2008 and SQL:2011 that most vendors applied them.
examples:
it is cool to see this question :) and the answer is quite simple http://www.contrib.andrew.cmu.edu/~shadow/sql/sql.txt but why talking about T-SQL or PL-SQL when the question is about SQL....
