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Oracle SQL Joins and Subqueries Flashcards

6 cards from real Oracle SQL practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 6 Oracle SQL Joins and Subqueries flashcards as text

  1. Which type of JOIN returns only rows where there is a match in BOTH tables?

    Answer: INNER JOIN

    An INNER JOIN returns only those rows where the join condition is satisfied in both tables, excluding unmatched rows.

  2. What does a LEFT OUTER JOIN return in Oracle SQL?

    Answer: All rows from the left table and matching rows from the right

    A LEFT OUTER JOIN returns all rows from the left table and NULL for unmatched columns from the right table.

  3. In Oracle SQL, what is the legacy syntax equivalent of a LEFT OUTER JOIN?

    Answer: table1, table2 WHERE table1.id = table2.id(+)

    Oracle's proprietary (+) operator placed on the right side of the condition creates a LEFT OUTER JOIN.

  4. What does a CROSS JOIN produce in Oracle SQL?

    Answer: A Cartesian product of all rows from both tables

    A CROSS JOIN produces a Cartesian product, pairing every row from the first table with every row from the second table.

  5. Which Oracle SQL subquery type returns a single value used in a WHERE clause comparison?

    Answer: Scalar subquery

    A scalar subquery returns exactly one row and one column, making it suitable for use with single-value comparison operators like =, >, <.

  6. What is a self-join in Oracle SQL?

    Answer: Joining a table to itself using aliases

    A self-join joins a table to itself using different aliases, commonly used for hierarchical data like employee-manager relationships.