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Oracle

1Z0-882 · Question #22

1Z0-882 Question #22: Real Exam Question with Answer & Explanation

The correct answer is C. The minimal number of rows possible are read.. See the full explanation below for the reasoning.

Question

Inspect the query: Mysql>SELECT dept_no, emp_no FROM employees JOIN dept _manager USING(emp_no) WHERE dept_no'd004'; 4 rows in set (0.00 sec) Mysql>EXPLAIN SELECT dept_no, emp_no FROM employees JOIN dept_manager USING (emp_no) WHERE dept_no='d004'; 2 rows in set (0.00 sec) Which two statements are true about the EXPLAIN output?

Exhibit

1Z0-882 question #22 exhibit

Options

  • AAll data for the result is read from the indexex.
  • BThe PRIMARY KEY is used for filtering in both tables.
  • CThe minimal number of rows possible are read.
  • DThe dept_manager table has 4 times as many rows than the employees table.

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