Postgres 11

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select version();

version

PostgreSQL 11.22 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 8.5.0 20210514 (Red Hat 8.5.0-20), 64-bit

SELECT 1

create table teachers (id serial primary key, name varchar, type varchar);
create table internal(id int);
create table external(id int);

CREATE TABLE

CREATE TABLE

CREATE TABLE

create or replace function trig_fun() 
returns trigger AS
$$
begin
if(new.type='IN') then
insert into internal values(new.id);
end if;

if(new.type='EX') then
insert into external values(new.id);

end if;
return new;
end;
$$
language plpgsql

CREATE FUNCTION

create trigger trig_on_insert 
after insert on 
teachers
for each row
execute procedure trig_fun()

CREATE TRIGGER

insert into teachers values(1,'A','EX');
insert into teachers values(2,'B','IN');
insert into teachers values(3,'C','EX');

INSERT 0 1

INSERT 0 1

INSERT 0 1

select * from teachers;

id
name
type

1
A
EX

2
B
IN

3
C
EX

SELECT 3

select * from internal;

id

2

SELECT 1

select * from external

id

1

3

SELECT 2