PL/SQL stands for “Procedural Language extension to SQL”. It provides a block structure for executable units of code. Maintenance of code is made easier with such a well-defined structure. Provides procedural constructs such as:
- Variables, constants, and data types
- Control structures such as conditional statements and loops
- Reusable program units that are written once and executed many times
PL/SQL defines a block structure for writing code. Maintaining and debugging code is made easier with such a structure because you can easily understand the flow and execution of the program unit. PL/SQL offers modern software engineering features such as data encapsulation, exception handling, information hiding, and object orientation. It brings state-of-the-art programming to the Oracle Server and toolset. PL/SQL provides all the procedural constructs that are available in any third-generation language (3GL).
PL/SQL Run- Time Architecture:
The diagram in the slide shows a PL/SQL blocks being executed by the PL/SQL engine.
- The PL/SQL engine resides in the Oracle database for executing stored subprograms
- The PL/SQL engine resides in the Oracle Forms client when you run client/server applications, or in the Oracle Application Server when you use Oracle Forms Services to run Forms on the Web
The PL/SQL engine is a virtual machine that resides in memory and processes the PL/SQL m-code instructions. When the PL/SQL engine encounters a SQL statement, a context switch is made to pass the SQL statement to the Oracle Server processes. The PL/SQL engine waits for the SQL statement to complete and for the results to be returned before it continues to process subsequent statements in the PL/SQL block. The Oracle Forms PL/SQL engine runs in the client for the client/server implementation, and in the application server for the Forms Services implementation. In either case, SQL statements are typically sent over a network to an Oracle Server for processing.
Advantages of PL/SQL:
Procedural Language Support:
Pl/SQL is a development tool not only for data manipulation features but also provide the conditional checking, looping or branching operations same as like other programming language.
Reduces Network Traffic:
This is one of the great advantages of PL/SQL. Because Pl/SQL nature is entire block of SQL statements execute into oracle engine all at once so its main benefit is reducing the network traffic.
PL/SQL is dealing with error handling. Its permits the smart way handling the errors and giving user friendly error messages, when the errors are encountered.
PL/SQL gives you control to declare variables and access them within the block. The declared variables can be used at the time of query processing.
Calculations I PL/SQL done quickly and efficiently without using oracle engines. This improves the transaction performance.
Applications are written in PL/SQL are portable in any operating system. PL/SQL applications are independence program to run any computer.
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