 
CREATE TABLE EMPLOYEE (
  empId int primary key Auto_Increment,
  emp_name TEXT NOT NULL,
  dept TEXT NOT NULL,
  Salary INTEGER
);

-- insert
INSERT INTO EMPLOYEE(emp_name, dept, Salary)  VALUES ('Thilak', 'DDDDD', 3900);
INSERT INTO EMPLOYEE(emp_name, dept, Salary) VALUES ('Clark',  'AAAAA', 4000);
INSERT INTO EMPLOYEE(emp_name, dept, Salary)  VALUES ('vivek', 'DDDDD', 7000);
INSERT INTO EMPLOYEE(emp_name, dept, Salary) VALUES ('Kodi', 'DDDDD', 14000);
INSERT INTO EMPLOYEE(emp_name, dept, Salary)  VALUES ('Dave',  'BBBBB', 3000);
INSERT INTO EMPLOYEE(emp_name, dept, Salary)  VALUES ('Rafi', 'AAAAA', 13500);
INSERT INTO EMPLOYEE(emp_name, dept, Salary)  VALUES ('Thani', 'BBBBB', 23000);
INSERT INTO EMPLOYEE(emp_name, dept, Salary)  VALUES ('Prem', 'CCCCC', 37000);
INSERT INTO EMPLOYEE(emp_name, dept, Salary)  VALUES ('Kalai', 'DDDDD', 3900);
INSERT INTO EMPLOYEE(emp_name, dept, Salary)  VALUES ('Sakthi', 'CCCCC', 5900);
INSERT INTO EMPLOYEE(emp_name, dept, Salary) VALUES ('Kanna', 'BBBBB', 11000);
INSERT INTO EMPLOYEE(emp_name, dept, Salary)  VALUES ('Arun', 'AAAAA', 10000);
INSERT INTO EMPLOYEE(emp_name, dept, Salary) VALUES ('Vignes', 'CCCCC', 6000);
INSERT INTO EMPLOYEE(emp_name, dept, Salary)  VALUES ('Jaga', 'AAAAA', 9000);
INSERT INTO EMPLOYEE(emp_name, dept, Salary)  VALUES ('Panda', 'BBBBB', 11000);
INSERT INTO EMPLOYEE(emp_name, dept, Salary)  VALUES ('Ava',   'CCCCC', 3500);


-- select dept, max(Salary) from EMPLOYEE group by dept; 


-- Select E.*, 
-- avg(Salary) over(partition by dept) as MAX_SALARY
-- from EMPLOYEE E;


-- Select e.empId, e.dept, e.emp_name, 
-- Max(e.Salary) over(partition by dept order by dept desc) as Salary
-- from EMPLOYEE e;


-- -- Row Number
-- select * from (
--   Select e.*, 
--   row_number() over(partition by dept order by Salary desc) as row_number_id
--   from EMPLOYEE e) ROWNUMBER
--   -- where ROWNUMBER.row_number_id = 2
--   ;

-- Select e.*, 
--   row_number() over(partition by dept order by Salary desc) as row_number_id
--   from EMPLOYEE e;

-- Rank FUnction
-- select * from 
-- (select *,
-- rank() over(partition by dept order by Salary desc) as rnk
-- from EMPLOYEE) as RANKK
-- where RANKK.rnk <3;
CREATE VIEW view_name AS
select emp_name, Salary, 
Avg(e.Salary) over(partition by dept order by dept desc) as AVG_Salary,
row_number() over(partition by dept order by Salary desc) as row_number_id,
rank() over(partition by dept order by Salary desc) as rankk,
dense_rank() over(partition by dept order by Salary desc) as dense__rank
from EMPLOYEE e;



select * from view_name;

-- select * from 
-- (select emp_name, dept, Salary, 
--   row_number() over(partition by dept order by Salary desc) as row__number
-- from EMPLOYEE) E1
-- where E1.row__number = 2;


-- select emp_name, count(*) from EMPLOYEE group by emp_name having count(*) > 1;


-- SELECT COUNT(DISTINCT Salary) FROM EMPLOYEE e2;
    
SELECT Salary
FROM EMPLOYEE e1
WHERE 3 = (
    SELECT COUNT(DISTINCT Salary)
    FROM EMPLOYEE e2 WHERE e2.Salary >= e1.Salary
);

SELECT  Salary
    FROM EMPLOYEE e2 WHERE Salary >= 14000;
-- select * from view_name;

-- -- Dense RANKK
-- select *, 
-- rank() over(partition by dept order by Salary desc) as rnk,
-- dense_rank() over(partition by dept order by Salary desc) as dn_rnk 
-- from EMPLOYEE;


-- -- -- LAG
-- select *, 
-- lag(salary, 2, 0) over(partition by dept order by empId) as prev_emp_salary
-- from EMPLOYEE;

-- -- LEAD
-- select *, 
-- lead(salary, 1, 0) over(partition by dept order by empId) as next_emp_salary
-- from EMPLOYEE;

created 2 years ago by Vivek Kumar

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About MySQL

MySQL is a open-source, free and very popular relational database management system which is developed, distributed and supported by Oracle corporation.

Key Features:

Open-source relational database management systems.
Reliable, very fast and easy to use database server.
Works on client-server model.
Highly Secure and Scalable
High Performance
High productivity as it uses stored procedures, triggers, views to write a highly productive code.
Supports large databases efficiently.
Supports many operating systems like Linux*,CentOS*, Solaris*,Ubuntu*,Windows*, MacOS*,FreeBSD* and others.

Syntax help

Commands

1. CREATE

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

Example

CREATE TABLE EMPLOYEE (
  empId INTEGER PRIMARY KEY,
  name TEXT NOT NULL,
  dept TEXT NOT NULL
);

2. ALTER

ALTER TABLE Table_name ADD column_name datatype;

Example

INSERT INTO EMPLOYEE VALUES (0001, 'Dave', 'Sales');

3. TRUNCATE

TRUNCATE table table_name;

4. DROP

DROP TABLE table_name;

5. RENAME

RENAME TABLE table_name1 to new_table_name1;

6. COMMENT

Single-Line Comments:

 --Line1;

Multi-Line comments:

   /* Line1,
   Line2 */

DML Commands

1. INSERT

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

Note: Column names are optional.

Example

INSERT INTO EMPLOYEE VALUES (0001, 'Ava', 'Sales');

2. SELECT

SELECT column1, column2, ...
FROM table_name
[where condition];

Example

SELECT * FROM EMPLOYEE where dept ='sales';

3. UPDATE

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

Example

UPDATE EMPLOYEE SET dept = 'Sales' WHERE empId='0001';

4. DELETE

DELETE FROM table_name where condition;

Example

DELETE from EMPLOYEE where empId='0001';

Indexes

1. CREATE INDEX

  CREATE INDEX index_name on table_name(column_name);

To Create Unique index:

  CREATE UNIQUE INDEX index_name on table_name(column_name);

2. DROP INDEX

DROP INDEX index_name ON table_name;

Views

1. Create a View

Creating a View:
CREATE VIEW View_name AS 
Query;

2. How to call view

SELECT * FROM View_name;

3. Altering a View

ALTER View View_name AS 
Query;

4. Deleting a View

DROP VIEW View_name;

Triggers

1. Create a Trigger

CREATE TRIGGER trigger_name trigger_time trigger_event
    ON tbl_name FOR EACH ROW [trigger_order] trigger_body
/* where
trigger_time: { BEFORE | AFTER }
trigger_event: { INSERT | UPDATE | DELETE }
trigger_order: { FOLLOWS | PRECEDES } */

2. Drop a Trigger

DROP TRIGGER [IF EXISTS] trigger_name;

Stored Procedures

1. Create a Stored Procedure

CREATE PROCEDURE sp_name(p1 datatype)
BEGIN
/*Stored procedure code*/
END;

2. How to call Stored procedure

CALL sp_name;

3. How to delete stored procedure

DROP PROCEDURE sp_name;

Joins

1. INNER JOIN

SELECT * FROM TABLE1 INNER JOIN TABLE2 where condition;

2. LEFT JOIN

SELECT * FROM TABLE1 LEFT JOIN TABLE2 ON condition;

3. RIGHT JOIN

SELECT * FROM TABLE1 RIGHT JOIN TABLE2 ON condition;

4. CROSS JOIN

SELECT select_list from TABLE1 CROSS JOIN TABLE2;