Which statement is true regarding the UNION operator?
A.
By default, the output is not sorted.
B.
Null values are not ignored during duplicate checking.
C.
Names of all columns must be identical across all select statements.
D.
The number of columns selected in all select statements need not be the same.
Explanation:
The SQL UNION query allows you to combine the result sets of two or more SQL SELECT
statements. It removes duplicate rows between the various SELECT statements.
Each SQL SELECT statement within the UNION query must have the same number of fields
in the result sets with similar data types.
B is the correct answer !
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B is answer
……….
Option B is correct.
By default output is sorted in the ascending order of the first column of the select clause
Null values are ignored
Names need not to be identical
The number of columns AND DATA TYPES selected in the select clause need to be same
B is correct- NULL values are NOT ignored.
B is correct. The only exception is UNION ALL where the rows will not be sorted.