What is the main difference between a UNION statement and a UNION ALL statement? 1. A UNION statement eliminates duplicate rows; a UNION ALL statement includes duplicate rows. 2. A UNION statement can be used to combine any number of queries; a UNION ALL statement can be used to combine a maximum of two queries. 3. A UNION statement can only combine queries that have parallel fields in the SELECT list; a UNION ALL statement can combine queries with differing SELECT list structures. 4. A UNION statement cannot be used with aggregate functions; a UNION ALL statement can be used with aggregate functions. 5. There is no difference between the two statements; they are interchangeable.

2 Answers   Saman Bank, Sonata,

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Initially question was asked to mention the types of indexes. Then asked about BITMAP INDEX and B-Tree Index

2 Answers   Polaris,

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What is sql partition?

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What are the different types of dbms?

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Can one improve the performance of sql*loader? : aql loader

0 Answers  

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What does count (*) mean in sql?

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Mention what pl/sql package consists of?

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what is the need of the cursor attribute notfound..(because using found attribute we can complete the task......found + negation operator = not found )

2 Answers   Tech Mahindra,

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what is the differnce between procedure and function? in both dml operations can work and in procedure through out parameter you can return value ,then what is the differce?

3 Answers   3i Infotech,

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What is the default value of CHAR type?

3 Answers   Bosch,

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What is spool?

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Does view contain data?

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