随笔分类 -  sql数据库

sql相关
摘要:基础语句: 模糊匹配: % 任意字符,_占位符 like '_t%'; 多字段排序: select winner,yr,subject from nobel where winner like 'Sir%' order by yr desc,winner asc 按照特殊排序,把chemistry, 阅读全文
posted @ 2024-09-10 23:37 HelloJacker 阅读(55) 评论(0) 推荐(0)
sql优化相关
摘要:去重数据 select distnct * from xx; 通过链接查询 join on 创建索引 create index index_name on example_table(statu); 分析索引 explain query plan 查询语句; analyze table_name; 阅读全文
posted @ 2024-08-06 09:22 HelloJacker 阅读(24) 评论(0) 推荐(0)