For instructions for reading the syntax diagrams in this chapter, see Oracle Database SQL Language Reference.
Each of these
CREATE statements has an optional
REPLACE clause. Specify
REPLACE to re-create an existing PL/SQL unit—that is, to change its declaration or definition without dropping it, re-creating it, and regranting object privileges previously granted on it. If you redefine a PL/SQL unit, the database recompiles it.
REPLACEstatement does not issue a warning before replacing the existing PL/SQL unit.
None of these
CREATE statements can appear in a PL/SQL block.
Reasons to use an
ALTER statement are:
To explicitly recompile a stored unit that has become invalid, thus eliminating the need for implicit runtime recompilation and preventing associated runtime compilation errors and performance overhead.
To recompile a unit with different compilation parameters.
For information about compilation parameters, see "PL/SQL Units and Compilation Parameters".
To enable or disable a trigger.
TYPE statement has additional uses. For details, see "ALTER TYPE Statement".
To drop an existing PL/SQL unit from the database, use one of these SQL statements: