Are UNION and UNION ALL the same ? Why ?
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No, UNION and UNION ALL are not same. UNION ALL will retain all the duplicate rows from tables in the final output while UNION will remove the duplicate rows from the final output.
UNION
UNION ALL
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A table STUDENT has 4 rows and 2 columns and another table TEACHER has 3 rows and 4 columns. How many rows and columns will be there if we obtain the Cartesian product of these two tables ?
What does UNION do ?
What does INTERSECT do ?
What does MINUS operation do ?