Topic 1 Question 8
You have two tables in an ANSI-SQL compliant database with identical columns that you need to quickly combine into a single table, removing duplicate rows from the result set. What should you do?
Use the JOIN operator in SQL to combine the tables.
Use nested WITH statements to combine the tables.
Use the UNION operator in SQL to combine the tables.
Use the UNION ALL operator in SQL to combine the tables.
解説
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コメント(5)
C is correct answer here.
The only difference between Union and Union All is that Union All will not removes duplicate rows or records, instead, it just selects all the rows from all the tables which meets the conditions of your specifics query and combines them into the result table.
👍 7saurabh18052020/11/05If you know SQL well enough, C is the answer
👍 2syu31svc2021/06/19C is correct
👍 1wilwong2021/07/20
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