Questenaتمرینی که نشان می‌دهد بعد چه چیزی را مرور کنید
سؤال 6

In PostgreSQL 18, what does SELECT ROW(NULL::int, 1) = ROW(NULL::int, 2); return?

  1. NULL
  2. falseپاسخ درست
  3. true
  4. It raises an error

توضیح

Row equality returns false as soon as any pair of corresponding fields is non-null and unequal, so 1 <> 2 settles the comparison and the null in the first field is never reached. NULL is only the answer when no pair is unequal and at least one pair involves a null - SELECT ROW(NULL::int, 1) = ROW(NULL::int, 1); does return NULL.

ادامهٔ این آزمون

شروع تمرین
سؤال 6: In PostgreSQL 18, what does SELECT ROW(NULL::int, 1) =… · SQL: NULL, Joins and Aggregates · Questena