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What will be the result of the following MySQL command?
What will be the result of the following MySQL command?
WHERE end_date IS NULL
AND NOT (title=’teller’ OR start_date < ‘2007-01-01’)
WHERE end_date IS NULL
AND NOT (title=’teller’ OR start_date < ‘2007-01-01’)
Answer & Solution
Correct Answer:
Option
A
This question is asking about how the given MySQL code will filter data from a table. Let's break it down:
WHERE end_date IS NULL
* This part of the code looks for rows where the 'end_date' column is empty or has a NULL value. * This typically means the employee is still working at the bank (their employment has not ended).
AND NOT (title=’teller’ OR start_date < ‘2007-01-01’)
* This part uses the NOT operator, which means we're looking for rows that don't match the conditions inside the parentheses.
* (title=’teller’ OR start_date < ‘2007-01-01’): This part checks for two things: * title=’teller’: It finds rows where the 'title' column is 'teller'. * start_date < ‘2007-01-01’: It finds rows where the 'start_date' is before 2007-01-01.
Putting it together:
The code is looking for rows that: * Have a NULL 'end_date' (they are still employed) * Are NOT either: * A 'teller' * Or started working before 2007-01-01
So the correct answer is Option A: The result set contains non-terminated employees who both are non-tellers and started working for the bank from 2007 or later.
WHERE end_date IS NULL
* This part of the code looks for rows where the 'end_date' column is empty or has a NULL value. * This typically means the employee is still working at the bank (their employment has not ended).
AND NOT (title=’teller’ OR start_date < ‘2007-01-01’)
* This part uses the NOT operator, which means we're looking for rows that don't match the conditions inside the parentheses.
* (title=’teller’ OR start_date < ‘2007-01-01’): This part checks for two things: * title=’teller’: It finds rows where the 'title' column is 'teller'. * start_date < ‘2007-01-01’: It finds rows where the 'start_date' is before 2007-01-01.
Putting it together:
The code is looking for rows that: * Have a NULL 'end_date' (they are still employed) * Are NOT either: * A 'teller' * Or started working before 2007-01-01
So the correct answer is Option A: The result set contains non-terminated employees who both are non-tellers and started working for the bank from 2007 or later.
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