difference between tsql, access sql and pl/sql

i am very confused

please help to clarify these differences!

are they all completely different languages? what开发者_StackOverflow中文版 is the overlap?

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T-SQL and PL/SQL are extensions of SQL. Overlap is entirely dependent upon which versions of Oracle and SQL Server you are comparing. IE:

WITH syntax: Has been supported by Oracle since 9i - SQL Server support started with 2005.

ANSI-92 support: Oracle 9i+ vs SQL Server 2005+

• Analytics (ROW_NUMBER, RANK, DENSE_RANK)
• CASE statement

Regex Support: Oracle 10g+ vs SQL Server 2005+ (requiring CLR enabling & CLR function created)

PIVOT/UNPIVOT: SQL Server 2005+ vs Oracle 11g+

COALESCE: Oracle 9i+ vs SQL Server 2000+

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TSQL - Transact SQL
PL/SQL - Is SQL for Oracle SQL Server
Access SQL - Is a hacked version of SQL

TSQL and PL/SQL are both based off of SQL ISO/ANSI Standards. It depends on the version of SQL Server(TSQL) or Oracle(PL/SQL) for what ISO/ANSI version they are using. See http://en.wikipedia.org/wiki/SQL for more info.

TSQL and PL/SQL just have extra functionality beyond ISO/ANSI SQL put in by the companies that made them. In general the ISO/ANSI SQL standard deal specifically with how you can Query a database and what structures you can have in the database (e.g. tables, triggers, stored procs, etc). TSQL and PL/SQL are true programming languages in that they can do loops and other things that a programming languages can do. Simply put TSQL and PL/SQL are turing complete and the ISO standards are not.

I am not sure about Access. I think it is just a hacked up version of SQL.

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There are SQL standards, that most RDBMSs follow, but in order to be competitive, most companies add their own extensions.

Many times these are extensions that are simply not in a standard.