select count（*） from student和select count（id） from student之间的区别是什么？
select count（*） from student和select count（id） from student之间的区别是什么？
相关考题：
（40）查找学生姓名及其所选修课程号和成绩，正确的 SQL 语句是A）SELECT sname FROM student, SELECT cno,grade FROM sc WHERE student.sno =sc.snoB） FROM sname,cno,grade FROM student,course WHERE student.sno =course.cnoC） SELECT sname ,canme,grade FROM student,course,sc WHERE student.sno =sc.sno and sc.cno=course.cnoD） SELECT sname ,cno,grade FROM student,sc WHERE student.sno =sc.sno
统计SB.dbf表中所有的主要设备数目。命令为:() A、count for 主要设备 to aB、cala count( 编号) for 主要设备 to aC、sel_ect count(*) from sb where 主要设备D、sel_ect count(*) as 小计 from sb where 主要设备
使用SQL语句从表STUDENT中查询所有姓王的同学的信息，正确的命令是：A）SELECT*FROM STUDENT WHERE LEFT（姓名，2）＝“王”B）SELECT*FROM STUDENT WHERE RIGHT（姓名，2）＝“王”C）SELECT*FROM STUDENT WHERE TRIM（姓名，2）＝“王”D）SELECT*FROM STUDENT WHERE STR(姓名，2)=“王”
若student 表中有一字段s_fenshu，数据类型为整型，保存每个学生的考试成绩，求全班平均分的正确做法是：A.把每个学生的 s_fenshu 手工进行相加，然后除以全班人数，得到平均分B.使用 select avg(s_fenshu) from studentC.使用 select sum(s_fenshu) from student / select count(*) from studentD.使用 select sum(s_fenshu) from student % select count(*) from student
根据SQL标准，下面哪条语句与select min(age) from student等效?()A select age from student where age >= min(age)B select distinct age from student where age >= all min(age)C select distinct a.age from student a where a.ageD select distinct a.age from student a where a.age
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 SCB select sno,count(cno) from studentC select a.sno,count(cno) from student a left outer join SCD select a.sno,count(cno) from SC left outer join student a
根据SQL标准，要查询表student中所有年龄age小于所有学生的平均年龄的记录，下面哪条语句适用?()A select * from student where ageB select * from student having ageC select * from student a where a.ageD select * from student a where (select avg(b.age) from student b ) >= a.age
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
查找学生姓名及其所选修课程的课程号和成绩,正确的SQL语句是A．SELECT sname FROM student,SELECT cno,grade FROM sc WHERE student.sno=sc.snoB．SELECT sname,cno,grade FROM student,course WHERE student.sno=course.cnoC．SELECT sname,cname,grade FROM student,course,sc WHERE student.sno=sc.sno and sc.cno=course,cnoD．SELECT sname,cno,grade FROM student,sc WHERE student.sno=sc.sno
对于数据表：student(sno,sname,sex,age,grade)，查询学习成绩为空的学生的学号和姓名，下面语句正确的是______。A．SELECT sno,sname FROM student WHERE gade=NULLB．SELECT sno,sname FROM student WHERE grade IS NULLC．SELECT sno,age FROM student WHERE grade IS NULLD．SELECT mo,age FROM student WHERE grade=NULL
查询选修课程在5门以上(含5门)的学生的学号、姓名和平均成绩，并按平均成绩降序排序，正确的命令是A．SELECT s．学号，姓名，平均成绩FROM student s，score sc WHERE s．学号=sc．学号 GROUP BY s．学号HAVING COUNT(*)=5 ORDER BY平均成绩DESCB．SELECT学号，姓名，AVG(成绩)FROM student s，score sc WHERE s．学号=sc．学号AND COUNT(*)=5 GR0UP BY学号ORDER BY 3 DESCC．SELECT s．学号，姓名，AVG(成绩)平均成绩FROM student s，score sc wHERE s．学号=sc．学号AND COUNT(*)=5 GROUP BY s．学号ORDER BY平均成绩DESCD．SELECT s．学号，姓名，AVG(成绩)平均成绩FROM student s，score sc WHERE s．学号=sc．学号 GROUP BY s．学号HAVING COUNT(*)=5ORDER BY 3 DESC
已知有关系“STUDENT”，则关系运算σANE＜80(STUDENT)用SQL语句表示为(52)。A．SELECT( * )FROM STUDENT WHERE AVE ＜ 80B．SELECT( * )FROM STUDENT HAVING AVE ＜ 80C．SELECT(AVE)FROM STUDENT WHERE AVE ＜ 80D．SELECT(AVE） FROM STUDENT HAVING AVE ＜ 80
列出EMP表中,从事每个工种(JOB)的员工人数() 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;
要找出籍贯是湖北或湖南的学生的姓名和性别，下述SQL语句正确的有哪三项（）。A、SELECT Sname，Ssex FROM Student WHERE Sdept=（‘湖南’，‘湖北’）；B、SELECT Sanme，Ssex FROM Student WHERE Sdept=’湖南’ORSdept=’湖北’；C、SELECT Sname，Ssex FROM Student WHERE Sdep tLIKE‘湖%’D、SELECT Sname，Ssex FROM Student WHERE Sdept LIKE‘%湖’；E、SELECT Sname，Ssex FROM Student WHERE Sdept IN（‘湖南’，‘湖北’）；
The STUDENT_GRADES table has these columns: STUDENT_ID NUMBER(12) SEMESTER_END DATE GPA NUMBER(4,3) The registrar has asked for a report on the average grade point average (GPA) for students enrolled during semesters that end in the year 2000. Which statement accomplish this? （）A、SELECT AVERAGE(gpa) FROM student_grades WHERE semester _ end '01-JAN-2000' and semester end 31-DEC-2000';B、SELECT COUNT(gpa) FROM student grades WHERE semester _ end '01-JAN-2000' and semester end 31-DEC-2000';C、SELECT MIN(gpa) FROM student grades WHERE semester _ end '01-JAN-2000' and semester end 31-DEC-2000';D、SELECT AVG(gpa) FROM student_grades WHERE semester _ end BETWEEN '01-JAN-2000' and '31-DEC-2000';E、SELECT SUM(gpa) FROM student grades WHERE semester _ end '01-JAN-2000' and semester end 31-DEC-2000';F、SELECT MEDIAN(gpa) FROM student_grades WHERE semester _ end '01-JAN-2000' and semester end 31-DEC-2000';
The STUDENT_GRADES table has these columns: STUDENT_ID NUMBER(12) SEMESTER_END DATE GPA NUMBER(4,3) The registrar requested a report listing the students' grade point averages (GPA) sorted from highest grade point average to lowest. Which statement produces a report that displays the student ID and GPA in the sorted order requested by the registrar? （）A、SELECT student_id, gpa FROM student_grades ORDER BY gpa ASC;B、SELECT student_id, gpa FROM student_grades SORT ORDER BY gpa ASC;C、SELECT student_id, gpa FROM student_grades SORT ORDER BY gpa;D、SELECT student_id, gpa FROM student_grades ORDER BY gpa;E、SELECT student_id, gpa FROM student_grades SORT ORDER BY gpa DESC;F、SELECT student_id, gpa FROM student_grades ORDER BY gpa DESC;
查询student表中的所有非空email信息，以下语句正确的是（）。A、Select email from student where email !=nullB、Select email from student where email not is nullC、Select email from student where email nullD、Select email from student where email is not null
若要检索“Student”数据表中的所有记录和字段，则SQL语句为（）A、Selec t姓名，性别 From StudentB、Select*From StudentC、Select 姓名，性别 From Student Where 姓名=“张山“D、Select*From Student Where 姓名=“张山“
下列SQL语句中，能够完成求某列最大值的是（）。A、SELECT AVG（Age） FROM StudentB、SELECT MAX（Age） FROM StudentC、SELECT MIN（Age） FROM StudentD、SELECT COUNT（*） FROM Student
下列查询语句中，错误的是（）。A、SELECT Sno， COUNT（*） FROM SC GROUP BY SnoB、SELECT Sno FROM SC GROUP BY Sno WHERE COUNT（*） 3C、SELECT Sno FROM SC GROUP BY Sno HAVING COUNT（*） 3D、SELECT Sno FROM SC GROUP BY Sno
数据库中有一张表名称为Student，有列Number，Name，Age，IDCard，Sex。主键为Number。要求查询所有男同学信息，下列哪个SQL语句是正确的？（）A、Select* From Student Where Sex=’男’B、Select* From Student Where Number NotIn（Select Number From Student Where Sex=’男’）C、Select* From Student Where NumberIn（Select Numbe rFrom Student Where Sex=’男’）D、Select* From Student Where Sex’男’
数据库中有一张表名称为Student，有列Number，Name，Age，IDCard，Sex。主键为Number。统计学生总人数，下列哪个SQL语句是正确的（）A、Select Count（1）From StudentB、Select Sum（*）From StudentC、Selec tAvg（*）From StudentD、Select Count（*）From Student
查询student表中的所有非空email信息，以下语句正确的是（）A、Select email from student where email!=nullB、Select email from student where emailnotisnullC、Select email from student where emailnullD、Select email from student where emailisnotnull
在Transact-SQL语法中，以下SELECT语句正确的是（）。A、SELECT * FROM studentB、SELECT * FROM student WHERE GETDATE（）C、SELECT * FROM student ORDER st_idD、SELECT * FROM student BY St_name
列出EMP表中，从事每个工种（JOB）的员工人数（）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;
查询名字中第2个字为“阳”的学生的姓名和学号，正确的是（）A、Select Sname，Sno from student where Sname like‘_阳%’；B、Select Sname，Sno from student where Sname like‘阳%’；C、Select Sname，Sno from student where Sname like‘_阳’；D、Select Sname，Sno from student where Sname like‘阳_%’；
问答题select count（*） from student和select count（id） from student之间的区别是什么？