test=# create table beginner (id serial primary key, val text);
CREATE TABLE
test=*# insert into beginner (val) values ('a line');
INSERT 0 1
test=*# insert into beginner (val) values ('next line');
INSERT 0 1
test=*# insert into beginner (val) values ('one more line');
INSERT 0 1
test=*# select * from beginner;
id | val
----+---------------
1 | a line
2 | next line
3 | one more line
(3 Zeilen)
test=*# delete from beginner where id = 2;
DELETE 1
test=*# insert into beginner values (2, 'a new line');
INSERT 0 1
test=*# select * from beginner;
id | val
----+---------------
1 | a line
3 | one more line
2 | a new line
(3 Zeilen)
test=*#