PL/SQL User's Guide and Reference

Advantages of PL/SQL

PL/SQL is a completely portable, high-performance transaction processing language that offers the following advantages:

support for SQL

higher productivity

better performance

portability

integration with Oracle

Support for SQL

SQL has become the standard database language because it is flexible, powerful, and easy to learn. A few English-like commands such as INSERT, UPDATE, and DELETE make it easy to manipulate the data stored in a relational database.

SQL is non-procedural, meaning that you can state what you want done without stating how to do it. Oracle determines the best way to carry out your request. There is no necessary connection between consecutive statements because Oracle executes SQL statements one at a time.

PL/SQL lets you use all the SQL data manipulation, cursor control, and transaction control commands, as well as all the SQL functions, operators, and pseudocolumns. So, you can manipulate Oracle data flexibly and safely.

Higher Productivity

PL/SQL adds functionality to non-procedural tools such as Oracle Forms and Oracle Reports. With PL/SQL in these tools, you can use familiar procedural constructs to build applications. For example, you can use an entire PL/SQL block in an Oracle Forms trigger. You need not use multiple trigger steps, macros, or user exits. Thus, PL/SQL increases productivity by putting better tools in your hands.

Moreover, PL/SQL is the same in all environments. As soon as you master PL/SQL with one Oracle tool, you can transfer your knowledge to other tools, and so multiply the productivity gains. For example, scripts written with one tool can be used by other tools.

Better Performance

Without PL/SQL, Oracle must process SQL statements one at a time. Each SQL statement results in another call to Oracle and higher performance overhead. In a networked environment, the overhead can become significant. Every time a SQL statement is issued, it must be sent over the network, creating more traffic.

However, with PL/SQL, an entire block of statements can be sent to Oracle at one time. This can drastically reduce communication between your application and Oracle. As Figure 1 - 5 shows, if your application is database intensive, you can use PL/SQL blocks and subprograms to group SQL statements before sending them to Oracle for execution.

Figure 1 - 5. PL/SQL Boosts Performance

PL/SQL also improves performance by adding procedural processing power to Oracle tools. Using PL/SQL, a tool can do any computation quickly and efficiently without calling on Oracle. This saves time and reduces network traffic.

Portability

Applications written in PL/SQL are portable to any operating system and platform on which Oracle runs. In other words, PL/SQL programs can run anywhere Oracle can run; you need not tailor them to each new environment. That means you can write portable program libraries, which can be reused in different environments.

Integration with Oracle

Both PL/SQL and Oracle are based on SQL. Moreover, PL/SQL supports all the SQL datatypes. Combined with the direct access that SQL provides, these shared datatypes integrate PL/SQL with the Oracle data dictionary.

The %TYPE and %ROWTYPE attributes further integrate PL/SQL with the data dictionary. For example, you can use the %TYPE attribute to declare variables, basing the declarations on the definitions of database columns. If a definition changes, the variable declaration changes accordingly at run time. This provides data independence, reduces maintenance costs, and allows programs to adapt as the database changes to meet new business needs.