Conversion Functions Oracle PLSQL

SQL>
SQL>
SQL> create table customer(
  2           cust_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          ,zip_4                             varchar2(4)
 11          ,area_code                         varchar2(3)
 12          ,phone                             varchar2(8)
 13          ,company_name                      varchar2(50)
 14  );
Table created.
SQL>
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(1, 'Allen', 'Joe','J','10 Ave','London','CA','11111','1111','111', '111-1111','Big Company');
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(2,'Ward','Sue','W','20 Ave','New York','NY','44444','4444','444', '436-4444','B Company');
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(3,'Jason','Pure','J','50 St','Longli','CA','55555','5555','555', '234-4444','C Company');
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(4,'Bird','Jill', null,'30 St','Pais','NY','22222','2222','222', '634-7733','D Company');
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(5,'Hill','Carl','H','19 Drive','A Town','CA','66666','6566','666', '243-4243','E Company');
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(6,'Peter','Yari','P','38 Ave','Small City','NY','77777','7777','777', '454-5443','F Inc');
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(7,'Joe','Paula','J','78 St. Apt 3A','Queen City','NY','32322','2323','888', '664-4333','E Inc');
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(8,'Chili','Steve','C','38 Ave Apt 62','Mili','CA','88888','8888','787', '456-4566','G Inc');
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(9,'Mona','Joe','M','930 Ave933','Kansas City','MO','12345','1234','412', '456-4563','H Inc');
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(10,'Hack','Kisi','H','Kings Rd','Bellmore','NY','54321','3898','516', '767-5677','I Inc');
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(11,'Bill','Jose','B','12 Giant Rd.','Newton','NJ','23454','1234','958', '123-7367','J Associates');
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(12,'Taker','Lawrence','T','1 Sask Rd.','Camp','NJ','19191','3298','928', '123-7384','K Company');
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(13,'Richer','Doris','R','213 Easy Street','WarPease','RI','34343','2112','501', '123-7384','L Inc');
1 row created.
SQL> insert into customer( cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(14,'Pete','Doris','P','9 Ave','New York','NY','45454','4222','112', '123-1234','M Company');
1 row created.
SQL>
SQL> select state from customer;
ST
--
CA
NY
CA
NY
CA
NY
NY
CA
MO
NY
NJ
NJ
RI
NY
14 rows selected.
SQL>
SQL> SELECT
  2   SUM ( decode ( state, 'NJ' , 1) ) as nj,
  3   SUM ( decode ( state, 'NY' , 1) ) as ny,
  4   SUM ( decode ( state, 'RI' , 1) ) as ri
  5  FROM customer;
        NJ         NY         RI
---------- ---------- ----------
         2          6          1
1 row selected.
SQL>
SQL>
SQL> drop table customer;
Table dropped.
SQL> --