在写嵌套查询语句时，如果能确定查询块只返回单行单列的单个值，查询块可以出现在单个属性名、单个表达式、单个常量，即单值表达式能够出现的任何地方。

A、模型层

B、数据访问层

C、业务逻辑层

D、表示层

A、SELECT 姓名,性别,所属院系,简历 FROM tStud WHERE 性别="女" AND 所属院系 IN("03","04")

B、SELECT 姓名,简历 FROM tStud WHERE 性别="女" AND 所属院系 IN("03", "04")

C、SELECT 姓名,简历 FROM tStud WHERE 性别="女" AND 所属院系="03" OR 所属院系="04"

D、SELECT 姓名,简历 FROM tStud WHERE (性别="女" AND 所属院系="03") OR 所属院系="04"

A. ORDER BY

B. WHERE

C. GROUP BY

D. HAVING

A、WITH avgach (eeid,avgachieve) AS ( SELECT eeid,AVG(achieve) FROM eeexam GROUP BY eeid ) SELECT COUNT(*) FROM avgach WHERE avgachieve>=80;

B、WITH avgach (eeid,avgachieve) ( SELECT eeid,AVG(achieve) FROM eeexam GROUP BY eeid ) SELECT COUNT(*) FROM avgach WHERE avgachieve>=80;

C、SELECT COUNT(*) FROM (SELECT eeid,avg(achieve) FROM eeexam GROUP BY eeid )AS avgach (eeid,avgachieve) WHERE avgachieve>=80;

D、SELECT COUNT(*) FROM (SELECT eeid,avg(achieve) FROM eeexam GROUP BY eeid ) avgach (eeid,avgachieve) WHERE avgachieve>=80;

E、SELECT dname, (SELECT COUNT(*) FROM examiner WHERE department.dname = examiner.erdepa) FROM department WHERE avgachieve>=80;

F、SELECT * FROM erexam NATURAL LEFT OUTER JOIN exampaper;

A、SELECT

B、FROM

C、WHERE

D、GROUP BY

E、HAVING

F、ORDER BY

G、LIMIT

H、OFFSET

I、WITH

J、FOR

K、WHILE

L、INDEX

M、CREATE

A、SELECT * FROM erexam NATURAL LEFT OUTER JOIN exampaper;

B、SELECT * FROM erexam NATURAL LEFT JOIN exampaper;

C、SELECT * FROM erexam NATURAL JOIN exampaper;

D、SELECT * FROM erexam OUTER JOIN exampaper;

E、SELECT * FROM erexam NATURAL OUTER JOIN exampaper;

F、SELECT * FROM erexam LEFT OUTER JOIN exampaper;