Manage Employment Data

practice update, alter, replace, insert keywords.

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

  1. 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
  2. 将titles_test表名修改为titles_2017

    1. alter table table-name operation-name to ....

      alter table titles_test rename to titles_2017;
  3. 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
    );
    
  4. 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);
  5. 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'
    )
    ;
    ;
  6. 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

  1. 更新table row的数据: update

    update table_name set  column_name = ... where col_name = ...;
  2. 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;
  3. 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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