单项选择题
A. WHERE
B. HAVING
C. RESTRICT
D. GROUP BY
E. ORDER BY
单项选择题 What is true about joining tables through an equijoin? （）
单项选择题 You need to calculate the total of all salaries in the accounting department. Which group function should you use? （）
单项选择题 You define a multiple-row subquery in the WHERE clause of an SQL query with a comparison operator "=". What happens when the main query is executed? （）