Oracle 18c

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Create Table Invoice (
InvoiceID Varchar2(6) PRIMARY KEY NOT NULL,
Quantity number(10) NOT NULL, 
Date_of_purchase Date NOT NULL,
Unit_Price number(5,2) NOT NULL, 
Amount number(10) NOT NULL,
payment_method Varchar(18) CHECK (payment_method in ('Cash','Card','Paypal')) NOT NULL,
email varchar2(255) default 'unknown@gmail.com' check (email like '%@%.%')
)
insert into Invoice
    values ('abc001', 10, sysdate, 1, 10, 'Cash', null)
1 rows affected

insert into Invoice
    values ('abc002', 10, sysdate, 1, 10, 'Cash', 'me@my.com')
1 rows affected

-- error
insert into Invoice
    values ('abc002', 10, sysdate, 1, 10, 'Cash', 'not valid')
ORA-02290: check constraint (FIDDLE_WCSSPELJXAWWAXTYTUTX.SYS_C00118466) violated

select * from Invoice


INVOICEID
QUANTITY
DATE_OF_PURCHASE
UNIT_PRICE
AMOUNT
PAYMENT_METHOD
EMAIL


abc001
10
23-MAR-20
1
10
Cash
null

abc002
10
23-MAR-20
1
10
Cash
me@my.com

INVOICEID	QUANTITY	DATE_OF_PURCHASE	UNIT_PRICE	AMOUNT	PAYMENT_METHOD	EMAIL
abc001	10	23-MAR-20	1	10	Cash	null
abc002	10	23-MAR-20	1	10	Cash	me@my.com