SQL Server 2019

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create table empsalary(empid int, month int , salary int);
insert into empsalary values(1,1,100);
insert into empsalary values(1,2,101);
insert into empsalary values(1,3,103);
create table emp(empid int , id int);
insert into emp values(1,1);
4 rows affected

CREATE TRIGGER TRG_Table1_DEL
    ON empsalary
    FOR DELETE
AS
    UPDATE emp SET id = NULL WHERE empid in (SELECT empid FROM DELETED)
    
select  *from empsalary


empid
month
salary


1
1
100

1
2
101

1
3
103


select  *from emp


empid
id


1
1


delete empsalary where month=1;
2 rows affected

select  *from empsalary;


empid
month
salary


1
2
101

1
3
103


select  *from emp;


empid
id


1
null