-- create
create table emp3(emp_id int(25),emp_name varchar(30),job_id varchar(10),salary int(20), department_id int (20),manager_id int(25));
-- insert
insert into emp3 values(1001,'priya','it_pro',10000,10,1001);
insert into emp3 values(1002,'nithya','fi_acc',17000,30,1005);
insert into emp3 values(1003,'reshma','pu_man',25000,20,1003);
insert into emp3 values(1004,'renu','sal_man',30000,40,1002);
insert into emp3 values(1005,'abi','it_pro',40000,10,1001);
-- fetch 
select *from emp3;
create table dept(department_id int(25), department_name varchar(20),manager_id int(25), location_id int(20));
insert into dept value(10,'it',1001,201);
insert into dept value(20,'purchasing',1003,202);
insert into dept value(30,'finance',1005,203);
insert into dept value (40,'sales',1002,205);
select *from dept;
select emp_name,job_id from emp3 where department_id IN(select department_id from dept where department_name='it');
select emp_name,salary from emp3 where manager_id not in (select manager_id from emp3 where department_id='30');
select emp_name, department_id from emp3 where manager_id not in(select manager_id from dept where salary<20000);
select department_id,max(salary)from emp3 group by department_id having max(salary)<=all(select max(salary) from emp3 group by department_id);
select department_id,max(salary)from emp3 group by department_id having max(salary)>=all(select max(salary) from emp3 group by department_id);
select emp_name,job_id, department_id from emp3 where exists(select *from dept where manager_id=emp_id); 

MySQL online editor

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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;