count与count(*)的区别是()。A、无区别B、count是聚合函数,count(*)不是聚合函数C、count统计空格而COUNT(×)不统计D、count(*)统计NULL值,而COUNT不统计

count与count(*)的区别是()。

  • A、无区别
  • B、count是聚合函数,count(*)不是聚合函数
  • C、count统计空格而COUNT(×)不统计
  • D、count(*)统计NULL值,而COUNT不统计

相关考题:

count与count(*)的区别是()。 A.无区别B.count是聚合函数,count(*)不是聚合函数C.count统计空格而COUNT(×)不统计D.count(*)统计NULL值,而COUNT不统计

编译如下Java程序片断:classtest{intcount=9;publicvoida(){intcount=10;System.out.println(count1=+count);}publicvoidcount(){System.out.println(count2=+count);}publicstaticvoidmain(Stringargs[]){testt=newtest();t.a();t.count();}}结果将()。A.不能通过编译B.输出: count1=10 count2=9C.输出:count1=9 count2=9

编译如下的Java程序片段:Classtest{Intcount=9;Publicvoida(){Intcount=10;System.out,println(count1=”+count);}Publicvoidcount(){System.out.println(count2=”+count);}Publicstaticvoidmain(Stringargs[]){Testt=newTest();t.a();t.count();}}结果是()A.不能通过编译B.输出:count1=10count2=9C.输出:count1=9count2=9

下面程序的正确输出是( )。 public class Hello { public static void main(String args[]) { int count, xPos=25; for ( count=1; count<=10; count++ ) { if ( count==5 ) break; System.out.println(count ); xPos += 10; } } }A.1 2 3 4B.1 3 4C.编译错误D.以上都不是

在SQL语言中,关于COUNT函数的下列用法中错误的是______。A.COUNT(ALL)B.COUNT(*)C.COUNT(成绩)D.COUNT(DISTINCT学号)

读者写者问题的解决方案如下所示。Begin————①————;read_count:=read_count+1;if read_count=1then P(wnte);————②————;读文件;————③————;read—count:=read—count—1;if read—count=Othen V(write);————④————;End假设信号量.mutex表示对read—count共享变量所关注的互斥区进行互斥,那么,①、②、③和④处应该填写的语句是A.P(mutex)、P(mutex)、V(mutex)、V(mutex)B.P(mutex)、V(mutex)、P(mutex)、V(mutex)C.V(mutex)、V(mutex)、P(mutex)、P(mutex)D.V(mutex)、P(mutex)、V(rnutex)、P(mutex)

数据库的“职工基本情况表”有“姓名”和“职称”等字段,要分别统计教授、副教授和其他人员的数量。请在空白处填入适当语句,使程序可以完成指定的功能。Private Sub command5_Click( )Dim db As DAO.DatabaseDim rs As DAO.RecordsetDim zc As DAO.FieldDim Count 1 As Integer,Count2 As Integer,Count3 As IntegerSett db=CurrentDb( )Set rs=db.OpenRecordset(“职工基本情况表”)Set zc=rs.Fields(“职称”)Count1=0:Count2=0:Count3=0Do While Not______Select Case zcCase Is=“教授”Count1=Count1+1Case Is=“副教授”Count2=Count2+1Case ElseCount3=Count3+1End Select______Looprs.Closese rs=NothingSet db=NothingMsgBox“教授:”Count 1“,副教授:”Count2“,其他:”Count 3End Sub

下面的哪些程序段可以正确地获得从命令行传递的参数的个数?() A.int count = args.length;B.int count = args.length-1;C.int count=0; while(args[count]!=null) count++;D.int count=0;while (!(args[count].equals(“”))) count++;

Dear friend, whenever you need help,(). A. count me outB. count in meC. count out meD. count me in

有如下程序: include using namespace std; class pumpkin{ public:pumpkin(){++count 有如下程序:include<iostream>using namespace std;class pumpkin{public:pumpkin(){++count;}~pumpkin(){--count;}static void total_count(){cout<<count<<"pumpkin(s)"<<end1;}private:static int count;};int pumpkin::count=0;int main(){pumpkin p1[10];pumpkin::total_count();return 0;}这个程序的输出结果是______。

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

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; HAVING COUNT(*)=2B.SELECT 仓库号,COUNT(*),AVG(工资)FROM 职工表; GROUP BY 仓库号 HAVING COUNT(*)=2C.SELECT 仓库号,COUNT(*),AVG(工资)FROM 职工表; GROUP BY 仓库号 SET COUNT(*)=2D.SELECT 仓库号,COUNT(*),AVG(工资)FROM 职工表; GROUP BY 仓库号 WHERE COUNT(*)=2

给定一个Java程序代码,如下:运行编译后,输出结果是()。A.count1=9count2=9B.count1=10count2=9C.count1=10count2=10D.count1=9count2=10

有如下程序:includeusing namespace std;class MyClass{public:MyClass(){++count;}~ 有如下程序: #include<iostream> using namespace std; class MyClass{ public: MyClass(){++count;} ~MyClass(){--count;} static int getCount(){return count;} private: static int count; }; int MyClass::count=0; int main(){ MyClA.121B.232C.221D.122

关于下面函数,哪一个是错误描述?defcount_letter_number(string):letter_count=0digit_count=0forchinstring:if'a'returnletter_count,digit_countA.函数能统计字符串中英文字母出现的次数B.letter_count+=1可以写做letter_count=letter_count+1C.letter_count+=1可以写做letter_count++D.函数能统计字符串中数字出现的次数

公用变量声明的语句是()。AStatic Count As BooleanBDim Count As IntegerCPublic Count As String * 6DOption Explicit

select count(*) from student和select count(id) from student之间的区别是什么?

fwrite函数的一般调用形式是()。A、fwrite(buffer,count,size,fp)B、fwrite(fp,size,count,buffer)C、fwrite(fp,count,size,buffer)D、fwrite(buffer,size,count,fp)

公用变量声明的语句是()。 A、Static Count As BooleanB、Dim Count As IntegerC、Public Count As String * 6D、Option Explicit

HQL不支持聚合函数有()A、count(*)B、avg(…)C、count(…)D、count(?)

有语句:COUNT EQU 256,下列四种叙述中,正确的是()。A、COUNT是变量B、COUNT占用一个字节存储单元C、COUNT是符号常数D、COUNT占用二个字节存储单元

编译如下Java程序片断:  class test{  int count = 9;  public void a(){    int count=10;  System.out.println("count 1 =" + count);  }  public void count(){  System.out.println("count 2 =" + count);  }  public static void main(String args[]){    test t=new test();    t.a();   t.count();   } }  结果将()。    A、不能通过编译B、输出: count 1 = 10 count 2 = 9C、输出:count 1 = 9 count 2 = 9

单选题For debugging purposes, you need to record how many times a given JSP is invoked before the user’ssession has been created. The JSP’s destroy method stores this information to a database. Which JSPcode snippet keeps track of this count for the lifetime of the JSP page?()A%! int count = 0; %% if ( request.getSession(false) == null ) count++; %B%@ int count = 0; %. % if ( request.getSession(false) == null ) count++; %C% int count = 0;. if ( request.getSession(false) == null ) count++; %D%@ int count = 0;. if ( request.getSession(false) == null ) count++; %E%! int count = 0;. if ( request.getSession(false) == null ) count++; %

问答题select count(*) from student和select count(id) from student之间的区别是什么?

单选题count与count(*)的区别是()。A无区别Bcount是聚合函数,count(*)不是聚合函数Ccount统计空格而COUNT(×)不统计Dcount(*)统计NULL值,而COUNT不统计

单选题编译如下Java程序片断:  class test{  int count = 9;  public void a(){    int count=10;  System.out.println("count 1 =" + count);  }  public void count(){  System.out.println("count 2 =" + count);  }  public static void main(String args[]){    test t=new test();    t.a();   t.count();   } }  结果将()。A不能通过编译B输出: count 1 = 10 count 2 = 9C输出:count 1 = 9 count 2 = 9

单选题编译如下的Java程序片段:  Class test{     Int count=9;     Public void a(){   Int count=10;   System.out,println(“count 1=” + count); }  Public void count(){   System.out.println(“count 2 =”+ count); }  Public static void main(String args[] ){   Test t=new Test();   t.a();   t.count(); } }  结果是()A不能通过编译B输出:count 1 =10  count 2=9C输出:count 1=9 count 2=9