單項(xiàng)選擇題

Which constraint can be defined only at the column level? （）

A. UNIQUE
B. NOT NULL
C. CHECK
D. PRIMARY KEY
E. FOREIGN KEY

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多項(xiàng)選擇題
In which two cases would you use an outer join? （）
A. The tables being joined have NOT NULL columns.
B. The tables being joined have only matched data.
C. The columns being joined have NULL values.
D. The tables being joined have only unmatched data.
E. The tables being joined have both matched and unmatched data.
F. Only when the tables have a primary key/foreign key relationship.
單項(xiàng)選擇題
The PRODUCTS table has these columns:
PRODUCT_ID NUMBER(4)
PRODUCT_NAME VARCHAR2(45)
PRICE NUMBER(8,2)
Evaluate this SQL statement:
SELECT *
FROM PRODUCTS
ORDER BY price, product _ name;
What is true about the SQL statement? （）
A. The results are not sorted.
B. The results are sorted numerically.
C. The results are sorted alphabetically.
D. The results are sorted numerically and then alphabetically.

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