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简介 select user_id from ( select id, user_id, product_name, status, client_id, date, count(1) over (partition by user_id) as num from order_info where 阅读全文
posted @ 2021-07-01 15:08
HDU李少帅
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简介 select id, user_id, product_name, status, client_id, date from ( select id, user_id, product_name, status, client_id, date, count(1) over (partitio 阅读全文
posted @ 2021-07-01 15:07
HDU李少帅
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简介 from 接 子查询 count(1) 统计个数 over (partition by user_id) 以user_id 进行分区 left join on 后面还可以加上where select a.id, a.is_group_buy, b.name as client_name fro 阅读全文
posted @ 2021-07-01 14:53
HDU李少帅
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简介 考察DATE_FORMAT 与 group 联立 order by 联立 select job, DATE_FORMAT(date, '%Y-%m') as mon, sum(num) as cnt from resume_info where date like '2025%' group 阅读全文
posted @ 2021-07-01 12:00
HDU李少帅
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简介 考察 over 从一行到另一行?? 先暂时这么记忆吧 select grade, sum(number) over(order by grade) t_rank from class_grade order by grade; 阅读全文
posted @ 2021-07-01 11:51
HDU李少帅
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简介 select concat(last_name, ' ', first_name) as Name from employees; 阅读全文
posted @ 2021-07-01 11:40
HDU李少帅
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简介 INSERT INTO actor values (1, 'PENELOPE', 'GUINESS', '2006-02-15 12:34:33'), (2, 'NICK', 'WAHLBERG', '2006-02-15 12:34:33') 阅读全文
posted @ 2021-07-01 11:38
HDU李少帅
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简介 删除emp_no重复的记录，只保留最小的id对应的记录。 DELETE FROM titles_test where id not in( select * from( select MIN(id) from titles_test group by emp_no )as a ) 阅读全文
posted @ 2021-07-01 11:34
HDU李少帅
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简介 修改数据 update titles_test set emp_no = replace(emp_no, 10001, 10005) where id = 5; update titles_test set to_date = NULL, from_date ='2001-01-01' whe 阅读全文
posted @ 2021-07-01 11:30
HDU李少帅
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简介 alter table titles_test rename to titles_2017; 阅读全文
posted @ 2021-07-01 11:17
HDU李少帅
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