Oracle Concepts - PL/SQL IF/THEN/ELSE
Oracle Tips by Burleson Consulting
PL/SQL IF/THEN/ELSE Statements
The IF/THEN statement checks a Boolean value or
expression and if true, executes the statements in the THEN clause. If the
condition is false, the statements in the THEN clause are skipped and execution
jumps to the END IF, and the expression that is checked must return a true or
false. It can be a simple Boolean variable or a compound expression joined with
AND/OR clauses, and the expression can even be a PL/SQL function that returns a
There is no requirement to surround the expression with
parenthesis but most developers use parentheses for clarity. The THEN clause
can contain a single or multiple statements, or a nested PL/SQL block. Here is
an example of a basic IF/THEN statement with a THEN clause.
if v_numb > 5 then
v_numb := 5;
v_other := 10;
In the statements above, the Boolean condition (v_numb >
5) must be true before the THEN clause is executed. If v_numb is equal to or
less than 5, or if it evaluates to NULL, the program control jumps to the
statement after the END IF clause. Note that the THEN clause can contain any
number of valid PL/SQL statements. The variable v_other and v_numb will not
change unless the condition is true.
Note: All the IF/THEN statements must end with an END
IF clause. The PL/SQL engine will continue to include statements in the THEN
clause until it encounters an END IF. If you get a compile error that states:
?found xxxx when expecting IF?, the compiler encountered an END statement before
it encountered the END IF. Simply find the end of you IF statement and close it
with an END IF to correct the problem.
Sometimes the program flow will want to branch one
direction if the condition is true and another direction if the condition is
false, and this is handled within the IF/THEN/ELSE statement.
Like the IF/THEN statement, the THEN clause statements
will only be executed if the condition is true. However if the condition is
false, the statements in the ELSE clause are executed. This is an either-or
if n_numb > 5 then
v _status :=
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After executing the example, the variable v_status will
be defined as either large or small. Note that the above statement could also
be written as two separate IF statements.
if n_numb > 5 then
v_status := ?large?; end if;
if n_numb <=5 then
v_status := ?small?; end if;
Programmatically, the results are the same, however the
two IF statements required two evaluations, while the IF/THEN/ELSE statement
requires only one evaluation.
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