PL/SQL has a BOOLEAN data type to store logical condition values: TRUE, FALSE, or NULL.
You declare it as shown here:
declare variable1_b BOOLEAN; ...
Because there is no corresponding SQL data type, you cannot use Boolean variables outside of pure PL/SQL.
Boolean variables can be assigned either directly by using values TRUE, FALSE, or NULL or as the results of logical expressions.
You can use Boolean variables for all conditional structures: IF, CASE, EXIT WHEN, and so on.
There was no need to include v_b = TRUE because the result of the comparison will also be a Boolean value.
SQL> SQL> declare-- w w w .j a v a2 s. c o m 2 v_b BOOLEAN:=false; 3 begin 4 v_b:=extract(year from sysdate)>2000; 5 if v_b 6 then 7 DBMS_OUTPUT.put_line('21st Century!'); 8 end if; 9 end; 10 / 21st Century! PL/SQL procedure successfully completed. SQL>