SQL learning alter add new field

summary

When developers maintain table when , We often encounter the scene of changing the structure of the table .
And that's where it comes in alter.
It should be noted that , Changing table Structure of , If a field is added , Then it needs to pass update To assign values to new fields .

Demo

create table Person (
	name string,
	age int
);

insert into  Person values
("AAA",16),
("BBB",10),
("CCC",20);

sql Code

--  Insert new field 
alter table Person add adult boolean;

--  Update data 
update Person SET adult=age>=18;

select * from  Person;

result

AAA|16|0
BBB|10|0
CCC|20|1