随笔分类 - SQL

MySQL分组聚合

摘要：-- 创建hq_kline表 delete from hq_kline CREATE TABLE hq_kline( id INT AUTO_INCREMENT PRIMARY KEY, finance_mic VARCHAR(16) NOT NULL, prod_code VARCHAR(64) 阅读全文

posted @ 2023-10-14 13:37 壹索007 阅读(24) 评论(0) 推荐(0) 编辑

SQL刷题牛客23

摘要：SQL1 top 2 -->结尾处limit 2 SQL13 in('1','3','5') 找的内容不连续 between 1 and 5 包含首尾，找的内容连续 is/is not NULL SQL18 select gender,university,count(device_id) user 阅读全文

posted @ 2022-11-08 12:30 壹索007 阅读(23) 评论(0) 推荐(0) 编辑

SQL刷题力扣

摘要：力扣584.寻找用户推荐人： select name from customer where referee_id!=2 or referee_id is not NULL; null值无法与确定的值作比较，用 is NULL 或者 is not NULL 判断力扣175.组合两个表： selec 阅读全文

posted @ 2022-11-07 17:52 壹索007 阅读(60) 评论(0) 推荐(0) 编辑