PostgreSQL part-1

TO BE KNOWN:

what is object?

• Real Time Entity
• Key and value pairs
• instance of class.

created table:

To get details about table coulmns:

\d employee;

movies=#\d employee;

output:

Insert

insert into employee values(123, 'Kavin', 'Software Engineer', 'DB', 25000);
insert into employee values(124, 'viyan', 'Software Engineer', 'AI', 27000);

cinemas=# select * from employee;

Add more rows in single insert statement:[TBD]

insert values into employee values(101, 'Arul', 'Team Lead', 'Front End', 35000), (102,'Agaran','Team Lead','DB',45000);

Specific column values:

select name from employee;

select name , designation from employee;

Change Table Name:

alter table employee rename to employees;

postgres=# alter table employee rename to employee;

Add more rows:

postgres=#   insert into employees values(111, 'Mugilan', 'Team Lead', 35000), (118,'pari','SQL Developer', 45000);

Learning: Selecet:

#1: slelect distrinct designation from employees;(with distrinct)

#2: slelect distrinct designation from employees;(without distrinct)

Where clause:

select * from employees where dept ='DB';

count of an team lead:

#3: where, and

select * from employees where dept='45000' and designation = 'SQL Developer';

4: where, or

select * from employees where dept='DEV' or designation = 'Manager';

Change dept as department:

#5: Not Equal to:

• select * from employee where dept <> 'DB';
• select * from employee where not dept = 'DB';
• select * from employee where dept != 'DB';

#6: > greater than:

select * from employee where salaey  28000;

#7: between:

select * from employee where salary between 19000 and 35000;

#8: in:

select * from employee where dept in ('DB', 'FE', 'AI'
);

select * from employee where dept not in ('DB', 'FE', 'AI'
);