COMPUTER SCIENCE AND ENGINEERING
SQL
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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existing queries
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one or more tables.
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Either A or B
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None of the above
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Detailed explanation-1: -A simple SELECT statement is the most basic way to query multiple tables. You can call more than one table in the FROM clause to combine results from multiple tables.
Detailed explanation-2: -In SQL we can retrieve data from multiple tables also by using SELECT with multiple tables which actually results in CROSS JOIN of all the tables. The resulting table occurring from CROSS JOIN of two contains all the row combinations of the 2nd table which is a Cartesian product of tables.
Detailed explanation-3: -A select query helps you retrieve only the data that you want, and also helps you combine data from several data sources. You can use tables and other select queries as data sources for a select query.
Detailed explanation-4: -Queries can only use data from one table at a time. A primary key field from one table appears in a second table.