Anyone can help? Thanks.
1. If a table contains a large number of records, use which one will be executed faster, where ... in , where exists, and why?
2.create table emp (
empid varchar2(5) constraint pk_emp_01 primary key,
lastnm varchar2(25),
firstnm varchar2(25),
salary number(10,4));
This primary key is a table constraint or column constraint? why? |
