September 2002
Intermediate to advanced
1024 pages
30h 52m
English
Content preview from Oracle PL/SQL Programming, Third EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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CASE Statements
New to PL/SQL in Oracle9i, the CASE statement allows you to select one sequence of statements to execute out of many possible sequences. CASE statements themselves are not new; they have long been implemented in other programming languages. They’ve been part of the SQL standard since 1992, although Oracle SQL didn’t support CASE until the release of Oracle8i, and PL/SQL didn’t support CASE until Oracle9i.
Oracle9i (and higher) supports the following two types of CASE statements:
- Simple CASE statement
Associates each of one or more sequences of PL/SQL statements with a value. Chooses which sequence of statements to execute based on an expression that returns one of those values.
- Searched CASE statement
Chooses which of one or more sequences of PL/SQL statements to execute by evaluating a list of Boolean conditions. The sequence of statements associated with the first condition that evaluates to TRUE is executed.
In addition to CASE statements, PL/SQL also supports CASE expressions. A CASE expression is very similar in form to a CASE statement, and allows you to choose which of one or more expressions to evaluate. The result of a CASE expression is a single value, whereas the result of a CASE statement is the execution of a sequence of PL/SQL statements.
Simple CASE Statements
A simple CASE statement allows you to choose which of several sequences of PL/SQL statements to execute based on the results of a single expression. Simple CASE statements take the following ...
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