CREATE TABLE  Employee  (
     EmpId  INTEGER NULL,
     EmpName  VARCHAR(255) NULL,
     EmpBOD  DATE,
     EmpJoiningDate  DATE,
     PrevExperience  INTEGER NULL,
     Salary  int NULL,
     Address  VARCHAR(255) NULL
);


INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(1,'Kieran Wilson','Aug 25, 2019','Feb 17, 2020',9,42655,'P.O. Box 653, 5711 Metus Street');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(2,'Keefe Byrd','Jul 6, 2019','May 13, 2020',4,51957,'3117 Interdum Rd.');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(3,'Brendan James','Apr 19, 2020','Mar 28, 2020',6,10816,'3519 Nunc Ave');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(4,'Jerry Beard','Apr 13, 2020','Jun 7, 2020',3,74119,'P.O. Box 536, 5943 Tellus St.');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(5,'Fitzgerald Bean','Apr 23, 2019','Nov 15, 2018',6,81052,'123-5228 Mauris Street');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(6,'Amir Salinas','Aug 22, 2020','Aug 13, 2020',9,58658,'732 In Street');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(7,'Justin Bender','Sep 28, 2020','May 3, 2020',10,66617,'148 Maecenas Rd.');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(8,'Colorado Cohen','Nov 22, 2019','May 22, 2020',3,15364,'882-1776 Vivamus Rd.');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(9,'Dolan Stokes','Apr 23, 2020','Mar 13, 2019',8,25884,'P.O. Box 844, 1589 Elit, Av.');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(10,'Byron Clements','Jul 19, 2019','Apr 27, 2020',3,17807,'P.O. Box 413, 8630 Vitae, St.');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(11,'Russell Griffin','Feb 2, 2019','Jun 25, 2019',3,64406,'Ap #279-8301 Magna Rd.');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(12,'Brady Carney','Dec 19, 2019','May 24, 2020',10,14806,'Ap #278-9852 Nibh. Street');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(13,'Keefe Klein','Aug 13, 2020','Aug 16, 2019',3,88833,'9814 Egestas Avenue');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(14,'Walker Simon','Feb 25, 2020','Jan 24, 2019',6,56364,'2335 Aliquam Ave');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(15,'Geoffrey Nunez','Jun 17, 2019','Jun 6, 2019',10,37364,'912-7721 Mus. Av.');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(16,'Myles Mcknight','Apr 15, 2020','Mar 7, 2020',9,91041,'477-2321 Commodo Avenue');
INSERT INTO Employee( EmpId , EmpName , EmpBOD , EmpJoiningDate , PrevExperience , Salary , Address ) VALUES(17,'Cadman Justice','Jul 9, 2019','Dec 29, 2019',2,34840,'P.O. Box 529, 8813 Proin Rd.');

SELECT * FROM Employee;

SELECT empname, salary FROM Employee WHERE salary >50000;

SELECT empname, prevexperience, salary FROM Employee WHERE prevexperience > 3;

alter table Employee add empjoinyear integer generated always as (extract (year from Empjoiningdate)) stored;

SELECT empjoinyear, round(AVG(salary),2)FROM Employee Group by empjoinyear;


alter table Employee add empjoinmonth integer generated always as (extract (month from Empjoiningdate)) stored;

SELECT empjoinmonth, round(AVG(salary),2)FROM Employee Group by empjoinmonth;

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About PostgreSQL

PostgreSQL is a open source relational database system and is also knows as Postgres.

Key Features:

  • Postgres is not only free and open-source but also it is highly extensible.
  • Custom Data types and funtions from various programming languaues can be introduced and the good part is compiling entire database is not required.
  • ACID(Atomicity, Consistency, Isolation, Durability) compliant.
  • First DBMS which implemented Multi-version concurrency control (MVCC) feature.
  • It's the default database server for MacOS.
  • It supports all major operating systems like Linux, Windows, OpenBSD,FreeBSD etc.

Syntax help

1. CREATE

CREATE command is used to create a table, schema or an index.

Syntax:

         CREATE TABLE table_name (
                column1 datatype,
                column2 datatype,
                ....);

2. ALTER

ALTER command is used to add, modify or delete columns or constraints from the database table.

Syntax

ALTER TABLE Table_name ADD column_name datatype;

3. TRUNCATE:

TRUNCATE command is used to delete the data present in the table but this will not delete the table.

Syntax

TRUNCATE table table_name;

4. DROP

DROP command is used to delete the table along with its data.

Syntax

DROP TABLE table_name;

5. RENAME

RENAME command is used to rename the table name.

Syntax

ALTER TABLE table_name1 RENAME to new_table_name1;

6. INSERT

INSERT Statement is used to insert new records into the database table.

Syntax

INSERT INTO table_name (column1, column2, column3, ...) VALUES (value1, value2, value3, ...);

7. SELECT

Select statement is used to select data from database tables.

Syntax:

SELECT column1, column2, ...
FROM table_name;

8. UPDATE

UPDATE statement is used to modify the existing values of records present in the database table.

Syntax

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

9. DELETE

DELETE statement is used to delete the existing records present in the database table.

Syntax

DELETE FROM table_name where condition;