Overview of PL/SQL
PL/SQL, the Oracle procedural extension of SQL, is a portable, high-performance transaction-processing language. This chapter explains its advantages and briefly describes its main features and its architecture.
PL/SQL Engine
The PL/SQL compilation and runtime system is an engine that compiles and runs PL/SQL units. The engine can be installed in the database or in an application development tool, such as Oracle Forms.
In either environment, the PL/SQL engine accepts as input any valid PL/SQL unit. The engine runs procedural statements, but sends SQL statements to the SQL engine in the database, as shown in Figure 1-1.
Figure 1-1 PL/SQL Engine
Typically, the database processes PL/SQL units.
When an application development tool processes PL/SQL units, it passes them to its local PL/SQL engine. If a PL/SQL unit contains no SQL statements, the local engine processes the entire PL/SQL unit. This is useful if the application development tool can benefit from conditional and iterative control.
For example, Oracle Forms applications frequently use SQL statements to test the values of field entries and do simple computations. By using PL/SQL instead of SQL, these applications can avoid calls to the database.
原创文章，作者：ItWorker，如若转载，请注明出处：https://blog.ytso.com/7272.html