Manage Employment Data
practice update, alter, replace, insert keywords.
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Create Table and insert Data
CREATE TABLE titles_test (
id int(11) not null primary key,
emp_no int(11) NOT NULL,
title varchar(50) NOT NULL,
from_date date NOT NULL,
to_date date DEFAULT NULL);
insert into titles_test values
('1', '10001', 'Senior Engineer', '1986-06-26', '9999-01-01'),
('2', '10002', 'Staff', '1996-08-03', '9999-01-01'),
('3', '10003', 'Senior Engineer', '1995-12-03', '9999-01-01'),
('4', '10004', 'Senior Engineer', '1995-12-03', '9999-01-01'),
('5', '10001', 'Senior Engineer', '1986-06-26', '9999-01-01'),
('6', '10002', 'Staff', '1996-08-03', '9999-01-01'),
('7', '10003', 'Senior Engineer', '1995-12-03', '9999-01-01');
CREATE TABLE `employees` (
`emp_no` int(11) NOT NULL,
`birth_date` date NOT NULL,
`first_name` varchar(14) NOT NULL,
`last_name` varchar(16) NOT NULL,
`gender` char(1) NOT NULL,
`hire_date` date NOT NULL,
PRIMARY KEY (`emp_no`));
Questions
将id=5以及emp_no=10001的行数据替换成id=5以及emp_no=10005,其他数据保持不变,使用replace实现,直接使用update会报错。(Using Update)
update titles_test set emp_no = REPLACE(emp_no, 10001, 10005) where id=5
将titles_test表名修改为titles_2017
alter table table-name operation-name to ....
alter table titles_test rename to titles_2017;
将所有获取奖金的员工当前的薪水增加10%
update salaries set salary = 1.1 * salary where to_date = '9999-01-01' and emp_no in (select emp_no from bouns );
获取Employees中的first_name,查询按照first_name最后两个字母,按照升序进行排列
select first_name from employees order by right(first_name,2);
按照dept_no进行汇总,属于同一个部门的emp_no按照逗号进行连接,结果给出dept_no以及连接出的结果, 预期结果:
CREATE TABLE `salaries` ( `emp_no` int(11) NOT NULL, `salary` int(11) NOT NULL, `from_date` date NOT NULL, `to_date` date NOT NULL, PRIMARY KEY (`emp_no`,`from_date`)); 如: INSERT INTO salaries VALUES(10001,85097,'2001-06-22','2002-06-22'); INSERT INTO salaries VALUES(10001,88958,'2002-06-22','9999-01-01'); INSERT INTO salaries VALUES(10002,72527,'2001-08-02','9999-01-01'); INSERT INTO salaries VALUES(10003,43699,'2000-12-01','2001-12-01'); INSERT INTO salaries VALUES(10003,43311,'2001-12-01','9999-01-01'); INSERT INTO salaries VALUES(10004,70698,'2000-11-27','2001-11-27'); INSERT INTO salaries VALUES(10004,74057,'2001-11-27','9999-01-01'); select avg(s1.salary) as avg_salary from salaries s1 where s1.to_date ='9999-01-01' and s1.salary not in (select max(s.salary) from salaries s where s.to_date ='9999-01-01' ) and s1.salary not in ( select min(s.salary) from salaries s where s.to_date ='9999-01-01' ) ; ;
按照dept_no进行汇总,属于同一个部门的emp_no按照逗号进行连接,结果给出dept_no以及连接出的结果, 预期结果:
dept_no
employees
d001
10001,10002
d002
10006
d003
10005
d004
10003,10004
d005
10007,10008,10010
d006
10009,10010
select d.dept_no, group_concat(d.emp_no ) as employees from dept_emp d group by d.dept_no;
Conclusion
更新table row的数据: update
update table_name set column_name = ... where col_name = ...;
更新table属性: alter
# add column alter table table_name add col_name, col_type; # drop column ALTER TABLE table_name DROP COLUMN column_name; # change column type ALTER TABLE table_name ALTER COLUMN column_name TYPE datatype;
SQL里面的group-concat() 函数相对于Spark里面的collect-list() 函数,把groupby分组后的列表里面的column的list聚集到一行里面
select d.dept_no, group_concat(d.emp_no ) as employees from dept_emp d group by d.dept_no;
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