OCP 1Z0 052 182

182. Which two statements are true regarding a PL/SQL package body? (Choose two.)

A.It cannot be created without a package specification.

B.It cannot invoke subprograms defined in other packages.

C.It can contain only the subprograms defined in the package specification.

D.It can be changed and recompiled without making the package specification invalid.

Answer: AD

package可以调用其它package中的过程。

package body 可以定义package specification中没有声明的过程。也就私有过程，仅供内部调用。

Data security

The methods of package definition enable you to specify which variables, cursors, and procedures are public and
private. Public means that it is directly accessible to the user of a package.
Private means that it is hidden from the user of a package.

http://docs.oracle.com/cd/E11882_01/server.112/e40540/srvrside.htm#CNCPT88935

A package body can be replaced and recompiled without affecting the specification. As a result, schema objects that reference a package's constructs (always
through the specification) need not be recompiled unless the package specification is also replaced. By using packages, unnecessary recompilations can be minimized, resulting in less impact on overall database performance.

Creation of PL/SQL Packages

You create a package in two parts: the specification and the body. The package specification declares all public constructs of the package, whereas thebody defines
all constructs (public and private) of the package.