Based on understanding of Vertica SQL/Postgre SQL, following piece of script I am implementing to enable primary key. But even after successful, error free execution of these statements, I can see Celonis allows INSERT with same values. Can you help me in understanding if I am falling short on something to enable primary key?

CREATE TABLE _CEL_ACTIVITY_PRIMARY_TEST(

    _case   varchar(25),

    activity_name varchar(100) not null,

    eventime DATETIME not null,

    PRIMARY KEY(_case)

);

SELECT * FROM _CEL_ACTIVITY_PRIMARY_TEST;

INSERT INTO _CEL_ACTIVITY_PRIMARY_TEST VALUES ('1234','act1','2022-08-22T09:46:46');