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Where is the sendmail.pid file kept?()

  • A、/
  • B、/var/adm/ras
  • C、/var/spool/mail
  • D、/etc

参考答案

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考题 设有 S ( 学号,姓名,性别 ) 和 SC ( 学号,课程号,成绩 ) 两个表,如下 SQL 语句检索选修的每门课程的成绩都高于或等于 85 分的学生的学号、姓名和性别,正确的是A)SELECT 学号 , 姓名 , 性别 FROM s WHERE EXISTS(SELECT * FROM sc WHERE SC. 学号 = S . 学号 AND 成绩 =85)B)SELECT 学号 , 姓名 , 性别 FROM s WHERE NOT EXISTS(SELECT * FROM sc WHERE SC. 学号 = S . 学号 AND 成绩 =85)C)SELECT 学号 , 姓名 , 性别 FRO M s WHERE EXISTS(SELECT * FROM sc WHERE SC. 学号 =S. 学号 AND 成绩 85)D)SELECT 学号 , 姓名 , 性别 FROM s WHERE NOT EXISTS(SELECT * FROM sc WHERE SC. 学号 =S. 学号 AND 成绩 85)

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考题 单选题查询选修C2课程号的学生姓名,下列SQL语句中错误的是(  )。A SELECT姓名FROM S WHERE EXISTS(SELECT*FROM SC WHERE学号=S.学号AND课程号=‘C2’)B SELECT姓名FROM S WHERE学号IN(SELECT学号FROM SC WHERE课程号=‘C2’)C SELECT姓名FROM S JOIN SC ON S.学号=SC.学号WHERE课程号=‘C2’D SELECT姓名FROM S WHERE学号=(SELECT学号FROM SC WHERE课程号=‘C2’)

考题 单选题查询出所有名字以’S’开始的员工()A select * from emp where ename in 'S%';B select * from emp where ename='S%';C select * from emp where ename like 'S%';D select * from emp where ename like 'S_';

考题 单选题设关系数据库中一个表S的结构为:S(SN,CN,grade),其中SN为学生名,CN为课程名,均为字符型;grade为成绩,数值型,下列()选项是正确的。A DELETE FROM S WHERE SN=’JULIE’B DELETE*FROM S WHERE SN=’JULIE’C DELETE FROM S WHERE SN=JULIED DELETE*FROM S WHERE SN=JULIE

考题 单选题可以删除学生表中学号为‘s2008005’的是()。A begin tran delete from学生表where学号=‘s2008005’ rollbackB begin tran delete from学生表where学号=‘s2008005’ commitC begin tran delete where学号=‘s2008005’ from 学生表 rollbackD begin tran delete where学号=‘s2008005’ commit