show databases;

use DBNAME;

show tables;

create table students (studentID int, firstName varchar(256), lastName varchar(256), age int);

insert into students values (123,'John','Doe',20);

select * from students;

insert into students values (124,'Jane','Doe',21),(125,'John','Roe',22),(126,'Jane','Roe',22),(127,'Johnny','Doe',19),(128,'Janie','Doe',23);

select * from students where age = 22;

select * from students where age = 22 and firstName = 'John';

select * from students where age = 22 or firstName = 'John';

update students set age = 25 where firstName = 'Jane';

delete from students where age = 25;

insert into students values (123,NULL,NULL,20);

create table newstudents (studentID int PRIMARY KEY, firstName varchar(256), lastName varchar(256), age int NOT NULL);

insert into newstudents values (123,'John','Doe',20);

insert into newstudents values (123,'John', NULL, NULL);

insert into newstudents values (124,'John', NULL, 23);

alter table newstudents drop column lastName;

alter table newstudents add column testscore int default 0;

alter table newstudents modify column testscore varchar(200);

insert into newstudents values (127,'John', 25,100);

drop table newstudents;