现有关系模式: EMP(empno,ename,mgr,sal,workday) 以及DEPT(deptno,dname,loc) ,以下视图中不可能更新的为________

2021-04-14

答案：

视图V4,由薪金超出所有雇员平均薪金以上的雇员组成

0
Consider the following query:SELECT dname, ename FROM dept d, emp e Where d.deptno=c.deptno ORDER BY dname, ename;What type of join is shown?() A: Self-join B: Equijoin C: Outerjoin D: Non-equijoin
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列出所有部门的部门名称和部门员工人数。如果部门没有员工，人数显示为0。正确的查询语句有_________。 A: SELECT dname,COUNT(ename) AS ecount FROM dept,emp WHERE emp.deptno(+)=dept.deptno GROUP BY dept.dname B: SELECT dname,(SELECT COUNT(*) AS ecount FROM emp WHERE emp.deptno=dept.deptno) FROM dept C: SELECT dname,COUNT(ename) AS ecount FROM dept LEFT JOIN emp ON emp.deptno=dept.deptno GROUP BY dept.dname D: SELECT dname,COUNT(*) AS ecount FROM dept LEFT JOIN emp ON emp.deptno=dept.deptno GROUP BY dept.dname
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以下语句正确的是() A: select sal+1 from emp; B: select sal*10,sal*deptno from emp; C: 不能使用运算符号 D: select sal*10,deptno*10 from emp;
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统计每个部门中人数的语句是？ A: select count(id) from emp order by deptno; B: select sum(id) from emp order by deptno; C: select count(id) from emp group by deptno; D: select sum(id) from emp group by deptno;
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设有一个关系：DEPT（DNO，DNAME），如果要找出倒数第三个字母为W，并且至少包含4个字母的DNAME，则查询条件子句应写成WHERE DNAME LIKE