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题解 | #删除记录（一）#

delete from exam_record where score<60 and (UNIX_TIMESTAMP(submit_time)-UNIX_TIMESTAMP(start_time))/60 <5

Mysql

2021-12-29

0 451

题解 | #获取有奖金的员工相关信息。#

select a.emp_no,a.first_name,a.last_name,b.btype,c.salary,replace(format((b.btype*c.salary/10),1),',','') as bonus from employees a,emp_bonus b,salari...

Mysql

2021-12-29

0 259

题解 | #获取当前薪水第二多的员工的emp_no以及其对应的薪水salary#

双重select聚合函数取max select a.emp_no,b.salary,a.last_name,a.first_name from employees a,salaries b where a.emp_no=b.emp_no and b.salary=( select max(...

Mysql

2021-12-18

0 336

题解 | #21年8月份练题总数#

device_id去重，模糊匹配日期，2个字段聚合count select count(distinct device_id去重，模糊匹配日期，2个字段聚合count) as did_cnt,count(question_id) as question_cnt from question_pract...

Mysql

2021-12-18

0 345