多项选择题
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
多项选择题 Whichtwostatementsaretrueregardingsinglerowfunctions?（）
多项选择题 YouneedtogeneratealistofallcustomerlastnameswiththeircreditlimitsfromtheCUSTOMERStable.Thosecustomerswhodonothaveacreditlimitshouldappearlastinthelist.Whichtwoquerieswouldachievetherequiredresult?（）
多项选择题 Wherecansubqueriesbeused?（）