UNION AND UNION ALL IN SQL

SQL> create table customer(cid int,cname varchar2(20),age int,sex varchar2(10),dob varchar2(20),address varchar2(20),phno int,email varchar2(20),annualincome varchar2(10),primary key(cid));

Table created.

SQL>  insert into customer values('&cid','&cname','&age','&sex','&dob','&address','&phno','&email','

&annualincome');

Enter value for cid: 1

Enter value for cname: john

Enter value for age: 58

Enter value for sex: male

Enter value for dob: 5/7/55

Enter value for address: german

Enter value for phno: 8548547895

Enter value for email: john2@gmail.com

Enter value for annualincome: 15000

1 row created.

SQL> select * from customer;

CID       CNAME      AGE    SEX       DOB    ADDRESS     PHNO           EMAIL      ANNUALINCOM

---------- -------------------- ----------       ---------- -------------------- -------------------- ---------- -----------------      

1             john            58    male       5/7/55   german      8548547895  john2@gmail.com    15000

2             mac            47     male       1/9/65   japan         854769485   mac33@gmail.com   14000

3             sam            21     male       1/7/91   greek         789456215   sam2@yahoo.com     10000

SQL> create table product(cid int,pid int,pname varchar2(20),brandname varchar2(20),price int,quantity int,primary key(cid,pid),foreign key(cid)  references customer);

Table created.

SQL> insert into  product  values('&cid','&pid','&pname','&brandname','&price','&quantity');

Enter value for cid: 1

Enter value for pid: 1

Enter value for pname: x220

Enter value for brandname: sony

Enter value for price: 2500

Enter value for quantity: 5

1 row created.

SQL> select * from product;

CID     PID     PNAME     BRANDNAME     PRICE     QUANTITY

------    ------   ------------   ---------------------   ----------    ------------------

1          1           x220         sony                        2500                 5

2          2           xpro          sony                       10000               3

3          3           star 3        samsung                  7000                 1

SQL>select cid  from customer union select cid from product;

CID

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1

2

3

4

SQL>select cid  from customer union all select cid from product;

CID

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1

2

3

4

1

2

3

4