Multiple choice technology databases

A UNION of two or more queries is valid provided the queries meet which of the following conditions? (Choose 3)

  1. All select lists in the UNION must have the same number of expressions

  2. Corresponding columns must have the same column names

  3. Corresponding columns must be of the same datatype or the server must be able to implicitly convert them

  4. Corresponding columns must be in the same order
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

For UNION queries to be valid, all SELECT statements must have the same number of columns (A), corresponding columns must be compatible datatypes (C), and columns must be in the same order (D). Column names need not match (B is false).

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