#sql

#sql SQL SET OPERATORS

-- 1. UNION - removes duplicates, keeps only one NULL
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SELECT emp_name FROM emp_hr
UNION
SELECT emp_name FROM emp_it;

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-- 2. UNION ALL - keeps duplicates, including all NULLs
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SELECT emp_name FROM emp_hr
UNION ALL
SELECT emp_name FROM emp_it;

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-- 3. INTERSECT - common rows only, NULL appears once if present in both
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SELECT emp_name FROM emp_hr
INTERSECT
SELECT emp_name FROM emp_it;

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-- 4. MINUS - rows in HR not in IT, NULL from HR may remain
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SELECT emp_name FROM emp_hr
MINUS
SELECT emp_name FROM emp_it;