Insert Update Delete Oracle PLSQL Tutorial

SQL>
SQL> create table emp(
  2           emp_no                 integer         primary key,
  3           lastname               varchar2(20)    not null,
  4           firstname              varchar2(15)    not null,
  5           midinit                varchar2(1),
  6           street                 varchar2(30),
  7           city                   varchar2(20),
  8           state                  varchar2(2),
  9           zip                    varchar2(5),
 10           shortZipCode                   varchar2(4),
 11           area_code              varchar2(3),
 12           phone                  varchar2(8),
 13           salary                 number(5,2),
 14           birthdate              date,
 15           startDate              date,
 16           title                  varchar2(20),
 17           dept_no                integer,
 18           mgr                    integer,
 19           region                 number,
 20           division               number,
 21           total_sales            number
 22  );
Table created.
SQL> -- emp Table Inserts:
SQL> insert into emp(emp_no, lastname, firstname, midinit, street, city, state, zip,shortZipCode, area_code, phone, birthdate, title)values
  2                      (1,'Z','Joy','R','1 Ave','New York','NY','12122','2333','212','200-1111','12-nov-1962','President');
1 row created.
SQL> insert into emp(emp_no, lastname, firstname, midinit, street, city, state, zip,shortZipCode, area_code, phone, salary, birthdate, startDate,title, dept_no, mgr, region, division, total_sales)valu
es
  2                      (2,'X','Lucy','J','1 Street','New York','NY','43552','6633','212','234-4444',7.75,'21-mar-1976','1-feb-1994','Sales Manager',2,1,100,10,40000);
1 row created.
SQL> insert into emp(emp_no, lastname, firstname, midinit, street, city, state, zip,shortZipCode, area_code, phone, salary, birthdate, startDate,title, dept_no, mgr, region, division, total_sales)valu
es
  2                      (3,'Y','Jordan','E','1 Drive','New York','NY','76822','8763','212','222-2222',7.75,'14-feb-1963','15-mar-1995','Sales Clerk',2,2,100,10,10000);
1 row created.
SQL>
SQL> select dept_no, lastname, salary from emp;
   DEPT_NO LASTNAME                 SALARY
---------- -------------------- ----------
           Z
         2 X                          7.75
         2 Y                          7.75
SQL>
SQL> UPDATE emp e1
  2     SET salary = 1.1 * (SELECT avg(salary) from emp e2 where e1.dept_no = e2.dept_no);
3 rows updated.
SQL>
SQL> drop table emp;
Table dropped.