Practice Test GeeksDA - Data Analyst Practice Test
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SQL and Database Querying Flashcards

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

Read the first 6 SQL and Database Querying flashcards as text

  1. Which SQL clause is used to filter rows after a GROUP BY operation?

    Answer: HAVING

    HAVING is used to filter aggregated results produced by GROUP BY, whereas WHERE filters individual rows before aggregation.

  2. What does a LEFT JOIN return?

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

    A LEFT JOIN returns all rows from the left table and the matched rows from the right table; unmatched right-table rows appear as NULL.

  3. Which aggregate function counts only non-NULL values in a column?

    Answer: COUNT(column_name)

    COUNT(column_name) counts only non-NULL entries in that column, while COUNT(*) counts all rows including those with NULLs.

  4. What is the purpose of the SQL DISTINCT keyword?

    Answer: Remove duplicate rows from the result set

    DISTINCT eliminates duplicate rows from query results, returning only unique value combinations.

  5. Which SQL statement is used to modify existing data in a table?

    Answer: UPDATE

    UPDATE changes existing records in a table based on a specified condition in the WHERE clause.

  6. What does the SQL ORDER BY clause do?

    Answer: Sorts result rows by one or more columns

    ORDER BY sorts query results in ascending (ASC, default) or descending (DESC) order based on specified columns.