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
正确答案:A,D
答案解析:有
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