多項選擇題

What are two reasons to create synonyms?（）

A. You have too many tables.
B. Your tables are too long.
C. Your tables have difficult names.
D. You want to work on your own tables.
E. You want to use another schema's tables.
F. You have too many columns in your tables.

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多項選擇題

Which three statements about subqueries are true?（）

A. A single row subquery can retrieve only one column and one row.
B. A single row subquery can retrieve only one row but many columns.
C. A multiple row subquery can retrieve multiple rows and multiple columns.
D. A multiple row subquery can be compared by using the “>” operator.
E. A single row subquery can use the IN operator.
F. A multiple row subquery can use the “=” operator.

單項選擇題

Which SQL statement returns a numeric value?（）

A. SELECT ADD_MONTHS(MAX(hire_Date), 6) FROM EMP;
B. SELECT ROUND(hire_date) FROM EMP;
C. SELECT sysdate-hire_date FROM EMP;
D. SELECT TO_NUMBER(hire_date + 7) FROM EMP;