1Mediumgeneralโฑ 45sWhat is the difference between INNER JOIN and LEFT JOIN?๐โผAThey always return the same rowsBINNER JOIN returns only matching rows from both tables; LEFT JOIN returns all rows from the left table plus matches (or NULLs) from the rightCLEFT JOIN never includes NULL valuesDINNER JOIN includes unmatched rows from the right table
2Mediumgeneralโฑ 45sWhat does a PRIMARY KEY constraint enforce?๐โผAAllows duplicate and NULL valuesBUniqueness and non-null for the column(s), and typically creates an index automaticallyCOnly enforces uniqueness across the entire databaseDPrevents the column from being indexed