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Chapter 1 Oracle PL/SQL Language Pocket Reference |
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PL/SQL includes conditional (IF) structures as well as sequential control (GOTO, NULL) constructs.
IF condition THEN executable statement(s) END IF;
For example:
IF caller_type = 'VIP' THEN generate_response('GOLD'); END IF;
IF condition THEN TRUE sequence_of_executable_statement(s) ELSE FALSE/NULL sequence_of_executable_statement(s) END IF;
For example:
IF caller_type = 'VIP' THEN generate_response('GOLD'); ELSE generate_response('BRONZE'); END IF;
IF condition-1 THEN statements-1 ELSIF condition-N THEN statements-N [ELSE else statements] END IF;
For example:
IF caller_type = 'VIP' THEN generate_response('GOLD'); ELSIF priority_client THEN generate_response('SILVER'); ELSE generate_response('BRONZE'); END IF;
The GOTO statement performs unconditional branching to a named label. It should be used rarely. At least one executable statement must follow the label (the NULL statement can be this necessary executable statement). The format of a GOTO statement is:
| GOTO label_name; |
The format of the label is:
| << label_name >> |
There are a number of scope restrictions on where a GOTO can branch control. A GOTO:
Can branch out of an IF statement, LOOP, or sub-block
Cannot branch into an IF statement, LOOP, or sub-block
Cannot branch from one section of an IF statement to another (from the IF/THEN section to the ELSE section is illegal)
Cannot branch into or out of a subprogram
Cannot branch from the exception section to the executable section of a PL/SQL block
Cannot branch from the executable section to the exception section of a PL/SQL block, although a RAISE does this
The NULL statement is an executable statement that does nothing. It is useful when an executable statement must follow a GOTO label or to aid readability in an IF-THEN-ELSE structure. For example:
IF :report.selection = 'DETAIL' THEN exec_detail_report; ELSE NULL; END IF;
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| 1.5 Variables and Program Data | 1.7 Loops |
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