Greetings,
A question about "combination of several columns " as primary key .
A table test (
col1 timestamp not null default now(),
col2 timestamp,
primary key (col1, col2)
);
If I setup primary key as the *combination* of (col1, col2), the col2
will be setup as "NOT NULL" automatically right?
(Although, I did not specify not null constraint for col2)
To allow *col2* to be NULL and make record combination (col1, col2)
unique, I should setup
unique (col1, col2) ?
Thanks,
Emi
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