How do I get my SQL to cascade only on certain conditions?

Question

How do I get my SQL to cascade only on certain conditions?

I want the child tuple to be deleted on cascade when parent column1 value is deleted only if column2C of CHILD is NOT equal to NULL .

Example :

create PARENT table(
    column1 varchar2(20) primary key, 
    column2 varchar2(20)
);

create CHILD table(
    column1C varchar2(20), 
    column2C varchar2(20) default NULL, 
    primary key(column1C,column2C)
);

alter table CHILD
    add constraint fk_const
    foreign key(column1C) references parent(column1)
    delete on cascade;

Answer 1

you can do it by means of triggers. more specifically you must write a trigger for the after delete event of table parent to check the condition and if it is true then delete the corresponding records in child table

Answer 2

Did you try using triggers? It would be simpler, transparent and you can disable them if you dont need them without modifying the definition. Give a proper example if needed and try creating them.