Untitled

01/02/2024
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Union operator and unio all operator

Union operator:
Union operator is used to combine the resultset of two or more tables:
union operator select only distinct values.
rules :

-number of columns same in both table.
-the columns must be same datatype.
-the column in every select clause must also in the same order and number of column must be same

syntax:- 
select columns from table1
union
select columns from table2

-- create table employee1(id int ,name varchar(30),age int ,salary int ,city varchar(30));
-- create table manager(id int ,name varchar(30),age int ,salary int ,city varchar(30));

insert into employee1 values(1,"ram",56,670000,"pune"),
(2,"sham",45,70000,"satara"),
(3,"gita",57,670000,"satara"),
(4,"sita",89,780000,"pune")

insert into manager values(1,"jiyu",78,200000,"nagpur"),
(2,"ajali",67,70000,"satara"),
(3,"nita",23,30000,"nashik"),
(4,"sita",89,780000,"pune")

select * from employee1
union
select * from manager;

select name,age from employee1
union
select name,age from manager;

select * from employee1 where salary >40000
union
select * from manager where salary >40000;

select * from employee1 where salary >(select salary from employeeinfo where id=3)
union
select * from manager where salary >40000;

select customer_id as id, age ,first_name as name from customers 
union 
select id,age,name from manager ;

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union all:

Union operator is used to combine the resultset of two or more tables:
union all select all rows including duplicate.
rules :

-number of columns same in both table.
-the columns must be same datatype.
-the column in every select clause must also in the same order and number of column must be same

syntax:- 
select columns from table1
union all
select columns from table2


select * from employee1 
union all
select * from manager ;

select customer_id as id, age ,first_name as name from customers 
union all
select id,age,name from manager ;

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toaday assignment

From the following tables, write a SQL query to find distinct salespeople and their cities. Return salesperson ID and city.

Sample table: Salesman
 salesman_id |    name    |   city   | commission 
-------------+------------+----------+------------
        5001 | James Hoog | New York |       0.15
        5002 | Nail Knite | Paris    |       0.13
        5005 | Pit Alex   | London   |       0.11
        5006 | Mc Lyon    | Paris    |       0.14
        5007 | Paul Adam  | Rome     |       0.13
        5003 | Lauson Hen | San Jose |       0.12

Sample table: Customer

 customer_id |   cust_name    |    city    | grade | salesman_id 
-------------+----------------+------------+-------+-------------
        3002 | Nick Rimando   | New York   |   100 |        5001
        3007 | Brad Davis     | New York   |   200 |        5001
        3005 | Graham Zusi    | California |   200 |        5002
        3008 | Julian Green   | London     |   300 |        5002
        3004 | Fabian Johnson | Paris      |   300 |        5006
        3009 | Geoff Cameron  | Berlin     |   100 |        5003
        3003 | Jozy Altidor   | Moscow     |   200 |        5007
        3001 | Brad Guzan     | London     |       |        5005

Sample Output:

salesman_id	city
5001	    New York
5002	    London
5002	    California
5006	    Paris
.....