表达式18＞15 && 18＜20的结果是（＞ A、true

关系代数表达式：其对应的SQL语句为（ ）。

A、SELECT eename,eeage,eesex FROM examinee WHERE eeage>=18 AND eeage<=23;<br> B、SELECT * FROM examinee WHERE eeage>=18 AND eeage<=23;<br> C、SELECT eename,eeage,eesex FROM examiner WHERE eeage>=18 AND eeage<=23;<br> D、SELECT eename,eeage,eesex FROM examinee WHERE 18<=eeage<=23;<br> E、SELECT eename,eeage,eesex FROM examinee WHERE eeage>=18 HAVING eeage<=23;<br> F、SELECT eename,eeage,eesex FROM examinee HAVING eeage>=18 AND eeage<=23;<br> G、SELECT eename,eeage,eesex FROM examinee HAVING eeage>=18 OR eeage<=23;<br> H、SELECT eename,eeage,eesex FROM examinee WHERE eeage>=18 OR eeage<=23;<br>

关系代数表达式：其对应的SQL语句为（ ）。

A、SELECT eename,eeage,eesex FROM examinee WHERE eeage>=18 AND eeage<=23;<br> B、SELECT * FROM examinee WHERE eeage>=18 AND eeage<=23;<br> C、SELECT eename,eeage,eesex FROM examiner WHERE eeage>=18 AND eeage<=23;<br> D、SELECT eename,eeage,eesex FROM examinee WHERE 18<=eeage<=23;<br> E、SELECT eename,eeage,eesex FROM examinee WHERE eeage>=18 HAVING eeage<=23;<br> F、SELECT eename,eeage,eesex FROM examinee HAVING eeage>=18 AND eeage<=23;<br> G、SELECT eename,eeage,eesex FROM examinee HAVING eeage>=18 OR eeage<=23;<br> H、SELECT eename,eeage,eesex FROM examinee WHERE eeage>=18 OR eeage<=23;<br>

体内维生素B缺乏，TPP效应是

A．<15％

B．>16%

C．<12%

D．>25%

E．>18%

关系代数表达式：其对应的SQL语句为（ ）。

A、SELECT eename,eeage,eesex FROM examinee WHERE eeage>=18 AND eeage<=23;> B、SELECT * FROM examinee WHERE eeage>=18 AND eeage<=23;> C、SELECT eename,eeage,eesex FROM examiner WHERE eeage>=18 AND eeage<=23;> D、SELECT eename,eeage,eesex FROM examinee WHERE 18<=eeage<=23;> E、SELECT eename,eeage,eesex FROM examinee WHERE eeage>=18 HAVING eeage<=23;> F、SELECT eename,eeage,eesex FROM examinee HAVING eeage>=18 AND eeage<=23;> G、SELECT eename,eeage,eesex FROM examinee HAVING eeage>=18 OR eeage<=23;> H、SELECT eename,eeage,eesex FROM examinee WHERE eeage>=18 OR eeage<=23;>

A、${ (age ge 18) and (age le 24) }

B、${ (age ge 18) , (age le 24) }

C、${ (age >= 18) , (age <= 24)> D、${ (age >= 18) ; (age <= 24)>

关系代数表达式：其对应的SQL语句为（ ）。

A、SELECT eename,eeage,eesex FROM examinee WHERE eeage>=18 AND eeage<=23;> B、SELECT * FROM examinee WHERE eeage>=18 AND eeage<=23;> C、SELECT eename,eeage,eesex FROM examiner WHERE eeage>=18 AND eeage<=23;> D、SELECT eename,eeage,eesex FROM examinee WHERE 18<=eeage<=23;> E、SELECT eename,eeage,eesex FROM examinee WHERE eeage>=18 HAVING eeage<=23;> F、SELECT eename,eeage,eesex FROM examinee HAVING eeage>=18 AND eeage<=23;> G、SELECT eename,eeage,eesex FROM examinee HAVING eeage>=18 OR eeage<=23;> H、SELECT eename,eeage,eesex FROM examinee WHERE eeage>=18 OR eeage<=23;>

若有关系R （A, B, C, D, E）和S（B，C, F, G）,则R与S自然联结运算后的属性列有（17）个，与表达式π1，3，6，7（σ3<6（R?S））等价的SQL语句如下: SELECT （18） FROM （19） WHERE （20）:

A.5

B.6

C.7

D.9

若有关系R （A, B, C, D, E）和S（B，C, F, G）,则R与S自然联结运算后的属性列有（17）个，与表达式π1，3，6，7（σ3<6（R?S））等价的SQL语句如下: SELECT （18） FROM （19） WHERE （20）:

A.5

B.6

C.7

D.9

A、where 18<=年龄<=22<br> B、where 18=<年龄=<22岁<br> C、where 年龄 BETWEEN 18 AND 22

D、where 年龄>=18 and <=22<br>