📄 que_020.htm
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<b>QUESTION 020
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<p>Examine the structure of the EMPLOYEES and DEPARTMENTS tables:
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<p><b>EMPLOYEES Table</b></p>
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<p><b>EMPLOYEE_ID NUMBER NOT NULL, Primary Key </b></p>
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<p><b>EMP_NAME VARCHAR2 (30) </b></p>
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<p><b>JOB_ID VARCHAR2 (20) </b></p>
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<p><b>SALARY NUMBER </b></p>
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<p><b>MGR_ID NUMBER References EMPLOYEE_ID COLUMN </b></p>
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<p><b>DEPARTMENT_ID NUMBER Foreign key to DEPARTMENT_ID </b></p>
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<p><b>DEPARTMENTS table</b></p>
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<p><b>DEPARTMENT_ID NUMBER NOT NULL, Primary Key </b></p>
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<p><b>DEPARTMENT_NAME VARCHAR2(30) </b></p>
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<p>MGR_ID NUMBER References MGR_ID column of the EMPLOYEES table
Evaluate this SQL statement:
<br><br>SELECT employee_id, e.department_id, department_name, salary <br>
FROM employees e, departments d <br>
WHERE e.department_id = d.department_id; <br>
</p>
<p>Which SQL statement is equivalent to the above SQL statement? </p>
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<p><b><input type="radio" name="AN" value="A"> A.</b></p>
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<p> SELECT employee_id, department_id, department_name,
salary<br> FROM employees <br>WHERE department_id IN (SELECT department_id <br>
FROM departments);
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<p><b><input type="radio" name="AN" value="B"> B.</b></p>
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<p> SELECT employee_id, department_id, department_name,
salary<br> FROM employees <br>NATURAL JOIN departments;
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<p><b><input type="radio" name="AN" value="C"> C.</b></p>
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<p> SELECT employee_id, d.department_id, department_name,
salary<br> FROM employees e <br>
JOIN departments d <br>
ON e.department_id = d.department_id;
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<p><b><input type="radio" name="AN" value="D"> D.</b></p>
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<p> SELECT employee_id, department_id, department_name,
Salary <br>
FROM employees <br>
JOIN departments <br>
USING (e.department_id, d.department_id);</p>
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