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سؤال 7

In PostgreSQL 18, what does SELECT coalesce(1, 1/0); return?

  1. NULL
  2. It raises a division-by-zero error
  3. 1پاسخ درست
  4. 0

توضیح

coalesce is not an ordinary function: like a CASE expression it evaluates only the arguments needed to determine the result, so once the first argument is known to be non-null, 1/0 is never evaluated. Expecting an error assumes the usual rule that all arguments of a function call are evaluated first.

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شروع تمرین
سؤال 7: In PostgreSQL 18, what does SELECT coalesce(1, 1/0); return? · SQL: NULL, Joins and Aggregates · Questena