评估此CREATE VIEW语句: CREATE VIEW emp_view AS SELECT SUM(salary) FROM employees; 以下哪个说法是的() A. 使用“雇员视图”视图不能更新“雇员”表中的数据 B. 使用“雇员视图”视图可以更新“雇员”表中的任何数据 C. 使用“雇员视图”视图不能删除“雇员”表中的记录 D. 使用“雇员视图”视图仅能...
评估此CREATE VIEW语句: CREATE VIEW emp_view AS SELECT SUM(salary) FROM employees; 以下哪个说法是的() A使用“雇员视图”视图不能更新“雇员”表中的数据 B使用“雇员视图”视图可以更新“雇员”表中的任何数据 C使用“雇员视图”视图不能删除“雇员”表中的记录...
例如:SELECT SUM(salary) FROM employees;字符串函数:使用CONCAT、SUBSTRING、UPPER、LOWER等函数来处理字符串数据。例如:SELECT CONCAT(first_name, ’ ', last_name) AS full_name FROM employees;日期函数:使用DATE_FORMAT、DATE_ADD、DATEDIFF等函数来处理日期数据。例如:SELECT DATE_FORMAT(birth_date, ‘%Y-%m...
select *,salary*12(1+ifnull(cpmmission_pct,0)) as 年薪 from employees order by 年薪 desc; 按照姓名长度显示姓名和工资 select length(last_name) 姓名长度,last_name,salary from employees order by 姓名长度 desc; 查询员工信息要求先按照工资升序再按照员工编号降序 select * from employees order by s...
mysql> SELECT last_name As 姓, first_name As 名 FROM employees; 方式二:使用空格 mysql> SELECT last_name 姓 , first_name 名 FROM employees; 案例:查询salary,显示结果为 out put mysql> SELECT salary As "out put" FROM employees; ///注意这边的双引号 ...
sum 和 SELECT SUM(salary) FROM employees; avg 平均值 SELECT AVG(salary) FROM employees; count 计算个数 SELECT COUNT(salary) FROM employees; SELECT SUM(salary) 和,AVG(salary) 平均,MAX(salary) 最高,MIN(salary) 最低,COUNT(salary) 个数 ...
SELECT column, group_function(column)FROM table[WHERE condition][GROUP BY group_by_expression][ORDER BY column];SELECT department_id, AVG(salary)FROM employeesGROUP BY department_id ; 2. 2 使用多个列分组 SELECT department_id dept_id, job_id, SUM(salary)FROM employeesGROUP BY department_id, ...
Command> SELECT SUBSTR (job_id, 4,10), SUM (salary) FROM employees GROUP BY SUBSTR (job_id,4,10); < PRES, 24000 > < VP, 34000 > < PROG, 28800 > < MGR, 24000 > < ACCOUNT, 47900 > < MAN, 121400 > < CLERK, 133900 > ...
60 T8 select sum(salary) from emp group by deptno; 问题二:这里查询结果为 T9 select * from dept; 问题三:这里查询的结果为 问题一的结果( b ) 问题二的结果是( d ) 问题三的结果是( e ) A: B: --- --- 1 50 1 50 2 60 2 55 C: D: --- --- 1 50 1 115 2 115 2 50 E...
C.select maximum(salary)from employees D.select MIN(salary)from employees 单项选择题 假设employees表中共有1000条数据,其中first_name有200条重复,执行SELECT COUNT(last_name)FROM employees;语句,会出现()结果。 A.结果显示800 B.结果显示1000 C.结果显示200 ...