how to make this query?

[Swirl]

Hello all,

I have the following table:

create table Sale(
bankname char(8) null,
controlename char(10) not null,
creditcardnummer numeric(19) null,
username char(10) not null,
accountnummer numeric(7) null,
constraint pk_username primary key(username)
)

I want to make a case/trigger where the following happens:
If the word "Creditcard" has been inserted in controlename then creditnummer must contain numbers else it will be NULL.

[skhanal]

Use CHECK Constraint.

[Swirl]

thank you for the reply