MySQL 5.7

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.
create table clas (
    id int primary key auto_increment,
    term smallint not null,
    subject varchar(10) not null,
    catalog smallint not null,
    component varchar(10) not null,
    section varchar(5)
);

create table clas_import (
    id int primary key auto_increment,
    term smallint not null,
    subject varchar(10) not null,
    catalog smallint not null,
    component varchar(10) not null,
    section varchar(5)
);
insert into clas values
    (1, 1730, 't1', 1, 'c1', 's1'),  -- match
    (2, 1730, 't2', 1, 'c2', 's2'),  -- match
    (3, 1730, 'tx', 1, 'cx', 'sx'),  -- no match
    (9, 1730, 'tx', 1, 'cx', 'sx'),  -- no match
    (4, 99, 'tx', 1, 'cx', 'sx');    -- no match but wrong term
    
    
insert into clas_import values
    (5, 1730, 't1', 1, 'c1', 's1'),
    (6, 1730, 't2', 1, 'c2', 's2'),
    (7, 1730, 't5', 1, 'c5', 's5'),
    (8, 99, 't4', 1, 'c4', 's4');
select clas.*
from clas
left join clas_import ci on
            clas.term      = ci.term AND
            clas.subject   = ci.subject AND
            clas.catalog   = ci.catalog AND
            clas.component = ci.component AND
            clas.section   = ci.section
where ci.id is null and
      clas.term = 1730


id
term
subject
catalog
component
section


3
1730
tx
1
cx
sx

9
1730
tx
1
cx
sx


delete clas
from clas
left join clas_import ci on
            clas.term      = ci.term AND
            clas.subject   = ci.subject AND
            clas.catalog   = ci.catalog AND
            clas.component = ci.component AND
            clas.section   = ci.section
where ci.id is null and
      clas.term = 1730;
select * from clas;


id
term
subject
catalog
component
section


1
1730
t1
1
c1
s1

2
1730
t2
1
c2
s2

4
99
tx
1
cx
sx