mysql:functional dependency

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mysql:functional dependency

0down vote First, a functional dependency in the form A->B means that, given one value for A, we can determine one and only one value for B. Both A and B represent sets of columns. (That's why they're written in uppercase letters.)…

[mysql] Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'loser.tank_admin.login_ip' which is not functionally dependent on columns in GROUP BY clause; this is

执行SQL: SELECT login_name,login_ip,sex FROM tank_admin GROUP BY login_name ; 时抛出异常. Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'loser.tank_admin.login_ip' which is not functionally dependent on columns in…

Mysql无法选取非聚合列

教程所示图片使用的是 github 仓库图片,网速过慢的朋友请移步>>> (原文)Mysql 无法选取非聚合列. 更多讨论或者错误提交,也请移步. 1. 前言最近升级博客,给文章页面底部增加了两个按钮,可以直接跳转到上一篇和下一篇.如下图所示: 实现这个功能的难点在于:数据库怎么选取出一条记录的前后两条相邻的记录? 2. 数据库设计关于我文章数据库的设计如下图所示: 可以看到,每条记录的身份是索引Id.因为之前有很多文章记录被删除了,所以,Id并不是连续的. 如果当前文章的索引值是3…

生产环境mysql的参数设置不一样，好好的程序，又出错

一.概述报错信息如下: org.springframework.jdbc.BadSqlGrammarException: ### Error querying database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'LS…

Install MySql on CentOS

Installing & Configuring MySQL Server This Howto will show you how to install MySQL 5.x, start the service, make sure the server starts on reboot, login via terminal, change the root database admin password, change the name of the root user, add a ne…

MySQL 聚合函数（四）检测功能依赖

源自MySQL 5.7 官方手册:12.20.4 Detection of Functional Dependence 本节提供了MySQL检测功能依赖的方式的几个示例.这些示例使用此表示法: {X} -> {Y} 将其理解为:“X唯一确定Y”,这也意味着Y在功能上依赖于X. 这里示例的几种检测功能依赖的方式为: Functional Dependencies Derived from Keys Functional Dependencies Derived from Multiple-Colu…

mysql升级后出现Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'userinfo.

安装了mysql5.7,用group by 查询时抛出如下异常: Expression #3 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'userinfo.t_long.user_name' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mod…