Consider the following database table: CREATE TABLE test ( one INTEGER, two…
2015
Consider the following database table:
CREATE TABLE test (
one INTEGER,
two INTEGER,
PRIMARY KEY (one),
UNIQUE (two),
CHECK (one >= 1 AND one <= 10),
CHECK (two >= 1 AND two <= 5)
);
How many data records/tuples can this table contain at most?
- A.
5
- B.
10
- C.
15
- D.
50
Attempted by 729 students.
Show answer & explanation
Correct answer: A
Answer: At most 5 rows.
Reasoning:
Column one is constrained by check(one >= 1 and <= 10), so it can take 10 distinct values (1 through 10).
Column two is constrained by check(two >= 1 and <= 5), so it can take 5 distinct values (1 through 5).
Both columns have uniqueness enforced (primary key on the first column and unique on the second), so each column must have distinct values across rows.
Therefore the maximum number of rows is limited by the column with the fewest distinct allowed values: min(10, 5) = 5.