Question

Given an empty table that was created using the query:

CREATE TABKE simple_tab (col1 char unique);

Which of the following queries will be executed successfully? Select all that apply.

Cosmo · Accepted Answer

UNIQUE constraint allows for NULL values.

Cosmo · Accepted Answer

INSERT INTO simple_tab VALUES ( null );

Cosmo · Accepted Answer

INSERT INTO simple_tab VALUES ( '''' );

Примечание: 4 одинарные кавычки

Cosmo · Accepted Answer

INSERT INTO simple_tab VALUES ( 'a' );