多项选择题
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.
相关考题
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单项选择题
In a SELECT statement that includes a WHERE clause, where is the GROUP BY clause placed in the SELECT statement?（）
A. Immediately after the SELECT clause
B. Before the WHERE clause
C. Before the FROM clause
D. After the ORDER BY clause
E. After the WHERE clause -
单项选择题
Examine the data of the EMPLOYEES table. EMPLOYEES (EMPLOYEE_ID is the primary key. MGR_ID is the ID of managers and refers to the EMPLOYEE_ID) Which statement lists the ID, name, and salary of the employee, and the ID and name of the employees manager, for all the employees who have a manager and earn more than 4000?（）
A.
B.
C.
D.
E.
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多项选择题
When should you create a role? （）
A.To simplify the process of creating new users using the CREATE USER xxx IDENTIFIED by yyy statement.
B.To grant a group of related privileges to a user.
C.When the number of people using the database is very high.
D.To simplify the process of granting and revoking privileges.
E.To simplify profile maintenance for a user who is constantly traveling.
