单项选择题
A.The indexed column is declared as NOT NULL.
B.The indexed columns are used in the FROM clause.
C.The indexed columns are part of an expression.
D.The indexed column contains a wide range of values.
单项选择题 Evaluate these two SQL statements: SELECT last_name, salary , hire_date FROM EMPLOYEES ORDER BY salary DESC; SELECT last_name, salary , hire_date FROM EMPLOYEESORDER BY 2 DESC; What is true about them?（）
单项选择题 Which SQL statement accepts user input for the columns to be displayed, the table name, and the WHERE condition?（）
多项选择题 Click the Exhibit button and examine the data in the EMPLOYEES table. Which three subqueries work?（）