基于"学生-选课-课程"数据库中的三个关系:
S(S#,SNAME,SEX,BIRTHYEAR,DEPT),主码为S#
C(C#,CNAME,TEACHER),主码为C#
SC(S#,C#,GRADE),主码为(S#,C#)
查找"由王建老师执教的操作系统课程的平均成绩、最高成绩和最低成绩",正确的SQL语句是
- A.SELECT AVG(GRADE), MAX(GRADE), MIN(GRADE) FROM C, SC GROUP BY CNAME = "操作系统" AND TEACHER = "王建"
- B.SELECT AVG(GRADE), MAX(GRADE), MIN(GRADE) FROM C, SC WHERE CNAME = "操作系统" AND TEACHER = "王建" AND SC.C# = C.C#
- C.SELECT AVG(GRADE), MAX(GRADE), MIN(GRADE) FROM C, SC HAVING CNAME = "操作系统" AND TEACHER = "王建" AND SC.C# = C.C#
- D.SELECT AVG(GRADE), MAX(GRADE), MIN(GRADE) FROM C, SC HAVING CNAME = "操作系统" AND TEACHER = "王建"
热度🔥307
有以下程序
#include
int fun(int (*s)[4], int n, int k)
{ int m, i;
m=s[0][k];
for(i=1; im)
m= s[i][k];
return m;
}
main()
{ int a[4][4]={{1,2,3,4},
{11,12,13,14},
{21,22,23,24},
{31,32,33,34}};
printf("%d\n",fun(a,4,0));
}
程序的运行结果是
我们所写的每条C语句,经过编译最终都将转换成二进制的机器指令。关于转换以下说法错误的是
以下自定义数据类型的语句中,正确的是( )。
多道程序设计的意义是