Consider the following code:
select 3 + 4 from departments;
The query result might look strange at first.
The outcome of the expression 3+4 is calculated for each row of the DEPARTMENTS table.
This is done four times, because there are four departments and we did not specify a WHERE clause.
Because the expression 3+4 does not contain any variables, the result (7) is obviously the same for every department row.
SQL> SQL>-- from w ww . j a v a 2 s. co m SQL> drop table departments; Table dropped. SQL> SQL> create table departments( 2 deptno NUMBER(2) primary key, 3 dname VARCHAR2(10) not null unique check (dname = upper(dname)), 4 location VARCHAR2(8) not null check (location = upper(location)), 5 mgr NUMBER(4)) ; SQL> SQL> insert into departments values (10,'ACCOUNTING','NEW YORK',7007); SQL> insert into departments values (20,'TRAINING', 'DALLAS', 7004); SQL> insert into departments values (30,'SALES', 'CHICAGO', 7006); SQL> insert into departments values (40,'HR', 'BOSTON', 7009); SQL> SQL> select 3 + 4 from departments; 3+4 --------- 00007.00 00007.00 00007.00 00007.00 SQL>