Database / SQLite Interview questions

What is a PRIMARY KEY in SQLite?

A PRIMARY KEY uniquely identifies each row in a table, and SQLite enforces that no two rows can share the same primary key value (unless declared otherwise for special cases like WITHOUT ROWID tables).

CREATE TABLE person (
    id INTEGER PRIMARY KEY,
    name TEXT
);

A notable SQLite-specific detail: declaring a column as INTEGER PRIMARY KEY (exactly that type, singular) makes that column an alias for the table's internal rowid — the fastest possible way to look up a row, since it directly maps to SQLite's internal B-tree key rather than requiring a separate index lookup.

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What does a PRIMARY KEY guarantee about a table's rows? That every row has a unique value in that column

✓ Correct! Well done.

That the column can contain NULL values freely

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Nothing; it's purely documentation in SQLite

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What special behavior does declaring a column as exactly `INTEGER PRIMARY KEY` trigger? Nothing special; it behaves like any other primary key

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It becomes an alias for the table's internal rowid, the fastest lookup path

✓ Correct! Well done.

It forces the column to always start at 100

✗ Not quite. Try again.

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Database / SQLite Interview questions

What is a PRIMARY KEY in SQLite?

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