The PL/SQL data types include the SQL data types, additional scalar data types, and composite data types. You define the composite data types. You can also define subtypes of the scalar data types.

Dynamic SQL is a programming methodology for generating and running SQL statements at runtime. It is useful when writing general-purpose and flexible programs like dynamic query systems, when writing programs that must run database definition language (DDL) statements, or when you do not know at compile time the full text of a SQL statement or the number or data types of its input and output variables.

The PL/SQL optimize level determines how much the PL/SQL optimizer can rearrange code for better performance. This level is set with the compilation parameter PLSQL_OPTIMIZE_LEVEL.

Exceptions (PL/SQL runtime errors) can arise from design faults, coding mistakes, hardware failures, and many other sources. You cannot anticipate all possible exceptions, but you can write exception handlers that let your program to continue to operate in their presence.

Conditional compilation lets you customize the functionality of a PL/SQL application without removing source text. For example, you can:

• Use new features with the latest database release and disable them when running the application in an older database release.

• Activate debugging or tracing statements in the development environment and hide them when running the application at a production site.

However:

• Oracle recommends against using conditional compilation to change the attribute structure of a type, which can cause dependent objects to "go out of sync" or dependent tables to become inaccessible.

  To change the attribute structure of a type, Oracle recommends using the ALTER TYPE statement, which propagates changes to dependent objects.

• Conditional compilation is subject to restrictions.

Bulk binding minimizes the performance overhead of the communication between PL/SQL and SQL, which can greatly improve performance.