Chapter 2: limitations of oracle_sql statements (where clause) and permutation data (order by clause)
Restrict data access:
Use numbers as conditions
Select ename,sal,deptno from emp where DEPTNO=10
Use characters as conditions, the string should be quoted only, case-sensitive!
Select ename,sal,deptno from emp where ename='king'
Select ename,sal,deptno from emp where ename='KING'
Use date as a condition, format sensitive!
Select ename,hiredate from emp where hiredate='23-JAN-82'
View the system date format with the help of the system function:
Select sysdate from dual
Select * from nls_database_parameters
Use single-line comparison symbols in where conditions
>
< , = ,>=, = and
