SQL
SQL is used to communicate with a database, it is the standard language for relational database management systems.
In detail Structured Query Language is a special-purpose programming language designed for managing data held in a relational database management system (RDBMS), or for stream processing in a relational data stream management system (RDSMS).
Originally based upon relational algebra and tuple relational calculus, SQL consists of a data definition language and a data manipulation language. The scope of SQL includes data insert, query, update and delete, schema creation and modification, and data access control. Although SQL is often described as, and to a great extent is, a declarative language (4GL), it also includes procedural elements.
PL/SQL
PL/SQL is a combination of SQL along with the procedural features of programming languages. It was developed by Oracle Corporation
Specialities of PL/SQL
T-SQL
Short for Transaction-SQL, an extended form of SQL that adds declared variables, transaction control, error and exceptionhandling and row processing to SQL
The Structured Query Language or SQL is a programming language that focuses on managing relational databases. SQL has its own limitations which spurred the software giant Microsoft to build on top of SQL with their own extensions to enhance the functionality of SQL. Microsoft added code to SQL and called it Transact-SQL or T-SQL. Keep in mind that T-SQL is proprietary and is under the control of Microsoft while SQL, although developed by IBM, is already an open format.
T-SQL adds a number of features that are not available in SQL.
This includes procedural programming elements and a local variable to provide more flexible control of how the application flows. A number of functions were also added to T-SQL to make it more powerful; functions for mathematical operations, string operations, date and time processing, and the like. These additions make T-SQL comply with the Turing completeness test, a test that determines the universality of a computing language. SQL is not Turing complete and is very limited in the scope of what it can do.
Another significant difference between T-SQL and SQL is the changes done to the DELETE and UPDATE commands that are already available in SQL. With T-SQL, the DELETE and UPDATE commands both allow the inclusion of a FROM clause which allows the use of JOINs. This simplifies the filtering of records to easily pick out the entries that match a certain criteria unlike with SQL where it can be a bit more complicated.
Choosing between T-SQL and SQL is all up to the user. Still, using T-SQL is still better when you are dealing with Microsoft SQL Server installations. This is because T-SQL is also from Microsoft, and using the two together maximizes compatibility. SQL is preferred by people who have multiple backends.
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