假定表table1中phone列有空值，则select count(*) from table1与select count(phone) from table1相等吗？ （）A、相等B、不相等

根据SQL标准，查询表student(sno,sname,sex,dept)中所有学生的选修课程数，其中选修记录在表SC(sno,cno,grade)中，两表中sno为关联字段。下面哪条语句合适?()

A select sno,count(cno) from SC

B select sno,count(cno) from student

C select a.sno,count(cno) from student a left outer join SC

D select a.sno,count(cno) from SC left outer join student a

检索最少有5名职工的每个部门的职工基本工资的总额( )。

A．SELECT 部门号,COUNT(*),SUM(基本工资) FROM 职工; HAVING COUNT(*)＞=5

B．SELECT 部门号,COUNT(*),SUM(基本工资) FROM 职工; GROUP BY 基本工资 HAVING COUNT(*)＞=5

C．SELECT 部门号,COUNT(*),SUM(基本工资) FROM 职工; GROUP BY 部门号 HAVING COUNT(*)＞=5

D．SELECT 部门号,COUNT(*),SUM(基本工资) FROM 职工; GROUP BY 部门号 WHERE COUNT(*)＞=5

已知基本表SC(S#，C#，GRADE)，则“统计选修了课程的学生人次数”的SQL语句为( )。

A．SELECT COUNT(DISTINCTS#)/FROM SC

B．SELECT COUNT(S#)/FROM SC

C．SELECTCOUNT(*)/FROM SC

D．SELECT COUNT (DISTINCT*)/FROM SC

若需统计zg表中车身厂的职工工资总和，下面语句正确的是( )。

A．SELECT SUM(基本工资)FROM zg

B．SELECT SUM(基本工资)FROM zgWHERE 单位=“车身厂”

C．SELECT COUNT(基本工资)FROM zg

D．SELECT COUNT(基本工资)FROM zgWHERE单位=“车身厂”

若需统计“选课”表中已经选修了课程的学生人数，下面语句正确的是( )。

A．SELECT COUNT(DISTINCT学生号)FROM选课

B．SELECT COUNT(学生号)FROM选课

C．SELECT COUNT(*)FROM选课

D．SELECT COUNT(DISTINCT*)FROM选课

要从选课表(学号、课程号、成绩)中查询选修了三门课程以上的学生学号，应使用的SELECT-SQL语句是

A．SELECT学号FROM选课表WHERE COUNT(*)＞=3

B．SELECT学号FROM选课表HAVING COUNT(*)＞=3

C．SELECT学号FROM选课表GROUP BY学号HAVING COUNT(*)＞=3

D．SELECT学号FROM选课表GROUP BY学号WHERE COUNT(*)＞=3

这段代码有什么不足之处?

try {

Connection conn = ...;

Statement stmt = ...;

ResultSet rs = stmt.executeQuery("select * from table1");

while(rs.next()) {

}

} catch(Exception ex) {

}

统计每个部门中人数( )

A.SELECT SUM(ID) FROM EMP GROUP BY DEPTNO;

B.SELECT SUM(ID) FROM EMP ORDER BY DEPTNO;

C.SELECT COUNT(ID) FROM EMP ORDER BY DEPTNO;

D.SELECT COUNT(ID) FROM EMP GROUP BY DEPTNO;

求至少有两个职工的每个仓库的平均工资______。

A．SELECT仓库号,COUNT(*)，AVG(工资)FROM职工表； HAVINGCOUNT(*)＞=2

B．SELECT仓库号,COUNT(*)，AVG(工资)FROM职工表； GROUPBY仓库号HAVING COUNT(*)＞=2

C．SELECT仓库号,COUNT(*)，AVG(工资)FROM职工表； GROUPBY仓库号SET COUNT(*)＞=2

D．SELECT仓库号,COUNT(*)，AVG(工资)FROM职工表； GROUPBY仓库号WHERE COUNT(*)＞=2

A.select job from emp;

B.select job,count(*) from emp;

C.select distinct job,count(*) from emp;

D.select job,count(*) from emp group by job;

E.select job,sum(empno) from emp group by job;