[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fg14dxnN-mgga7-uhR8cPiyqbpv9slg7zwzsBqInI5_U":3},{"answer":4,"createTime":5,"id":6,"options":7,"origin":12,"question":16,"related":17,"source":27,"type":28},[],"2026-04-12 09:05:04",338744884,[8,9,10,11],">all dname='Sales'","<any dname<>'Sales'",">any dname='Sales'","<all dname<>'Sales'",{"courseId":13,"courseImg":14,"courseName":15},"53e1d2ef4961cca8eea3e23969ad2cb9","https:\u002F\u002Ftihai-oss-cloud.itihey.com\u002Fimg\u002F03a579384a6dc297c89809b582fcc767.png","默认课程","某企业人事管理系统中有如下关系模式:员工表Emp(eno,ename,age,sal,dname),其中的属性分别表示员工号、员工姓名、年龄、工资和部门名称;部门表Dept(dname,phone),其中的属性分别表示部门名称和联系电话.现需要查询其他部门比销售部门(Sales)所有员工年龄都要小的员工姓名及年龄,对应的SQL 语句如下: select ename, age from Emp where age 【空白】 (select age from Emp where dname=' Sales' ) and 【空白】 ; 上面SQL语句中留空处的答案为以下哪个",[18,29,38,47,56,65,74,77,89,100],{"answer":19,"createTime":5,"id":20,"options":21,"question":26,"source":27,"type":28},[],338744878,[22,23,24,25],"外模式定义功能","检索、插入、修改和删除功能","模式定义功能","数据库的完整性定义功能","DBMS提供的DDL功能不包括( )","v1",0,{"answer":30,"createTime":5,"id":31,"options":32,"question":37,"source":27,"type":28},[],338744879,[33,34,35,36],"select A, B, D from R inner join S on R.C=S.C","select A,B,D from R,S where R.C=S.C","select A,B,D from R full outer join S on R.C=S.C","select A,B,D from R natural join S","设有关系R(A,B,C)和S(C,D),与关系代数表达式\u003Cimg src=\"https:\u002F\u002Ftihai-oss-cloud.itihey.com\u002Fimg\u002Fc73567bcff81d19ffe19733661c5803e.png\">不等价的SQL语句是哪个",{"answer":39,"createTime":5,"id":40,"options":41,"question":46,"source":27,"type":28},[],338744880,[42,43,44,45],"子查询返回的是多个值","子查询不返回值","子查询返回的是单个值","子查询返回的是布尔值","在嵌套查询中,用>、<、=>、=<、=、<>等比较运算符引出子查询的条件是什么",{"answer":48,"createTime":5,"id":49,"options":50,"question":55,"source":27,"type":28},[],338744881,[51,52,53,54],"having子句","group by子句","where子句","order by子句","对分组查询结果进行筛选的是( ),其条件表达式中可以使用集函数",{"answer":57,"createTime":5,"id":58,"options":59,"question":64,"source":27,"type":28},[],338744882,[60,61,62,63],"数据的物理独立性","数据的逻辑独立性","程序的逻辑独立性","程序的物理独立性","在数据库系统运行维护阶段,通过重建视图能够实现( )",{"answer":66,"createTime":5,"id":67,"options":68,"question":73,"source":27,"type":28},[],338744883,[69,70,71,72],"启用视图缓存优化","自动更新基表统计信息","阻止插入不符合视图条件的数据","强制使用索引查询","创建视图时使用WITH CHECK OPTION的作用是什么",{"answer":75,"createTime":5,"id":6,"options":76,"question":16,"source":27,"type":28},[],[8,9,10,11],{"answer":78,"createTime":5,"id":79,"options":80,"question":87,"source":27,"type":88},[],338744885,[81,82,83,84,85,86],"having子句的作用对象是基本表或者视图","having子句必须跟在group by子句之后,如果没有group by子句就不能有having子句","where子句和having子句不能同时出现","where子句的作用对象是分组结果","where子句的作用对象是基本表或视图","having子句的作用对象是分组结果","下列关于where子句和having子句的描述中,错误的是哪几个",1,{"answer":90,"createTime":5,"id":91,"options":92,"question":99,"source":27,"type":88},[],338744886,[93,94,95,96,97,98],"索引可以加速写操作,但会减慢读操作","索引属于三级模式中的内模式","表上创建的索引越多越好","索引可以加速所有类型的查询","索引会占用额外的存储空间","索引可以加速特定类型的查询","关于索引的描述,以下哪些说法正确",{"answer":101,"createTime":5,"id":102,"options":103,"question":110,"source":27,"type":88},[],338744887,[104,105,106,107,108,109],"模式包括若干基本表","模式包括若干视图和部分基本表","外模式包括若干视图和部分基本表","模式包括若干存储文件","内模式包括若干存储文件","内模式包括若干基本表和存储文件","在关系数据库中,下列描述正确的有哪些"]