Join in mysql

Simple join in mysql
Select table1.columnname, table2.columnname from table1 join table2 ON table1.columnname=table2.columnname

Example-
Table 1- emp

id	name	city	designation	departmentid
			1	ajay sharavat	noida	manager	1
			2	Vineet Butola	noida	developer	1
			3	sandeep kumar	noida	developer	2
			4	Sashank Singh	delhi	admin	2
			5	Ambrish Singh	noida	developer	1
			6	Aamir	delhi	support	1
			7	vishal sharavat	noida	developer	3
			8	vinay singh	delhi	developer	4
			9	monu	noida	support	10

Table2-department

id	name
			1	It
			2	support
			3	HR
			4	Sales
			5	Marketing

Join Operation

SELECT emp.name, emp.designation, department.department_name
FROM `emp` JOIN department ON emp.departmentid = department.id

Output

name	designation	department_name
ajay sharavat	manager	It
Vineet Butola	developer	It
Ambrish Singh	developer	It
Aamir	support	It
sandeep kumar	developer	support
Sashank Singh	admin	support
vishal sharavat	developer	HR
vinay singh	developer	Sales

Inner Join and Cross joins performs the same operation. Just replace JOIN to INNER JOIN or CROSS JOIN.

LEFT JOIN





Triggers in Mysql

delimiter $$
CREATE trigger triggername before/after INSERT/UPDATE/DELETE ON tablename
FOR each
ROW
BEGIN
sql query
END

Example:
delimiter $$
CREATE trigger myfirsttrigger before INSERT ON emp
FOR each
ROW
BEGIN
INSERT INTO department VALUES ('', NEW.name);
END