What does the UNION operation automatically eliminate in SQL?
Question
What does the UNION operation automatically eliminate in SQL?
Solution
The UNION operation in SQL automatically eliminates duplicate rows from the results. Here are the steps of how it works:
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When a UNION operation is performed between two tables, SQL first retrieves the data from these tables.
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It then combines the results into a single result set.
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After combining, SQL automatically removes any duplicate rows from this result set.
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The final result is a table that includes every distinct row from both of the original tables.
Please note that if you want to keep duplicate rows in your result set, you can use UNION ALL instead of UNION.
Similar Questions
What is the purpose of the SQL UNION operator?
What does the UNION operation automatically eliminate in SQL?Null values.Duplicate tuples.Relations with different schemas.Operations on virtual relations.
What is the purpose of the SQL UNION operator?OptionsCombines rows from two or more tables, including duplicatesCombines rows from two or more tables, removing duplicatesSorts rows in a tableDeletes rows from a table
A UNION query is which of the following?Combines the output from multiple queries and must include the same number of columns.Combines the output from no more than two queries and must include the same number of columns.Combines the output from multiple queries and does not include the same number of columns.Combines the output from no more than two queries and does not include the same number of columns.
In which scenario would using UNION ALL be preferable over UNION in SQL?Question 16Answera.When you want to filter out NULL values from the result setb.When you want to sort the combined result set based on a specific columnc.When you want to eliminate duplicate rows from the combined result setd.When you want to merge result sets while preserving duplicate rows
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