多选题Which two statements are true regarding subqueries? （）AA subquery can retrieve zero or more rowsBOnly two subqueries can be placed atone levelCA subquery can be used only in SQL query statementsDA subquery can appear on either side of a comparison oper
题目
多选题
Which two statements are true regarding subqueries? （）
A
A subquery can retrieve zero or more rows
B
Only two subqueries can be placed atone level
C
A subquery can be used only in SQL query statements
D
A subquery can appear on either side of a comparison operator
E
There is no limit on the number of subquery levels in the WHERE clause of a SELECT statement