mysql

```
drop database learn;
create database learn;
show databases;
use learn;
show tables;
-- #################### CREATE
CREATE TABLE users (
      id int PRIMARY KEY NOT NULL AUTO_INCREMENT,
  first_name varchar(25) not null,
  last_name varchar(25)not null,
  salary decimal(5, 2) check (salary>100),
  age int(3),
  department varchar(25) DEFAULT 'front'
);

-- #################### describe
describe users;

-- #################### insert
insert into users (first_name,last_name,salary) values ("moataz","mohammady",70);
insert into users (first_name,last_name,salary) values ("moataz","mohammady",200);
insert into users (first_name,last_name,salary) values ("moataz","mohammady",250);
insert into users (first_name,last_name,salary) values ("moataz","mohammady",300);
insert into users (first_name,last_name,salary) values ("moataz","mohammady",400);
insert into users (first_name,last_name,salary) values ("moataz","mohammady",500);
insert into users (first_name,last_name,salary) values ("mohamed","mohammady",500);
insert into users (first_name,last_name,salary) values ("zaki","mohammady",500);
insert into users (first_name,last_name,salary) values ("zaki2","mohammady",500);
insert into users (first_name,last_name,salary) values ("zahraa","mohammady",500);
insert into users (first_name,last_name,salary) values ("mohammady","mohammady",500);
insert into users (first_name,last_name,salary , department) values ("moataz","mohammady",400 ,'back');
insert into users (first_name,last_name,salary , department , age ) values ("moataz","mohammady",400 ,'back' , 30);


-- #################### select
select * from users ;

select * from users where id = 1;
select * from users where salary > 200;
select * from users where salary > 200 and  salary < 500 ;

select * from users where department = 'back';


-- https://www.w3schools.com/sql/sql_wildcards.asp
select * from users where first_name like 'za%';
select * from users where first_name like '________y%';
select * from users where first_name like '%y';

select * from users where age is not null ;
select * from users where age is null order by salary ;
select * from users where age is null order by salary desc;

-- #################### delete
delete from users where first_name='zaki2';


-- #################### update
update users set salary=900 where first_name="moataz";
select * from users ;
```