ibps-so 2016 · Question 47 of 394

The customer master of Chandrabhaga Urban Bank carries a column for the PAN. For some customers the PAN has been furnished and is recorded. For some it has not yet been furnished, though it exists and will be recorded when it is produced. For some — certain minors and certain non-resident cases — no PAN exists at all, so that the column can never be lled. The database administrator has left the column un lled in both the second and the third case, and has warned the programmers that a comparison written against such a column will not behave as a comparison against a blank string or a zero would behave. A null value in a database is correctly described as:

1. AA value of zero for a numeric column and a string of length zero for a character column
2. BA string consisting of one or more space characters, of the width declared for the column
3. CThe default value declared for the column, which the system substitutes whenever no value is supplied
4. DA marker signifying that the value is unknown, missing or inapplicable — not zero and not a blank string, and such that any comparison made with it yields the truth value unknown rather than true or falseCorrect
5. EA special value that compares equal to every other null, so that two rows both lacking the value are treated as matching