mysql execute info: SeaSoonKeun changed the title I encountered some problems when I was using Drill 1.20.2 to connect MySQL database fail to execute multi-table left join queries in MySQL when using Drill 1.20.2 Feb 17, 2023 Sign up for free to join this conversation on GitHub. Alread...
AI代码解释 mysql>select*from grade;+---+---+---+---+|id|sno|courseName|grade|+---+---+---+---+|1|202001|高数一|90||2|202003|高数二|88||3|202003|英语一|77||4|202004|英语二|79||5|202002|C++语言设计|87||6|202005|Java面向对象基础|98||7|202006|算法分析与实现|76||8|2...
I have two working queries: QUERY 1 SELECT agent.name, COUNT(open_result.id_open_event) AS open FROM open_result INNER JOIN open_event ON open_result.id_open_event = open_event.id INNER JOIN agent ON open_result.id_agent = agent.id ...
MySQL中的JOIN类型主要包括INNER JOIN、LEFT JOIN、RIGHT JOIN和FULL OUTER JOIN，各自的作用如下：1、INNER JOIN（内连接）：返回两个表中满足连接条件的匹配行。仅当左表和右表都有匹配时，结果才会出现在查询结果中。2、LEFT JOIN（左连接）：返回左表所有行，即使在右表中没有匹配的行。对于右表中没有匹配...
今天在Mysql官网(参考博客1)看到一段话: At the parser stage, queries with right outer join operations are converted to equivalent queries containing only left join operations. In the general case, the conversion is performed such that this right join: 代码语言:javascript 代码运行次数:0 运行 AI代码...
MySQL中查询缓存优化 概述 开启Mysql的查询缓存,当执行完全相同的SQL语句的时候,服务器就会直接从缓存中读取结果,当数据被修改,之前的缓存会失效,修改比较频繁的表不适合做查询缓存。 操作流程 1)客户端发送一条查询给服务器; 2)服务器先会检查查询缓存,如果命中了缓存,则立即返回存储在缓存中的结果。否则进入下一...
RIGHT EXCLUDING JOIN, andOUTER EXCLUDING JOIN, respectively. Some may argue that 5, 6, and 7 are not really joining the two tables, but for simplicity, I will still refer to these as Joins because you use a SQL Join in each of these queries (but exclude some records with aWHEREclause...
David LaneHugh E. Williams
Compare those results to the otherwise equivalent queries withJOIN ... ON: mysql>SELECT*FROMt1LEFTJOINt2ON(t1.a=t2.a);+---+---+---+---+|a|b|a|c|+---+---+---+---+|1|x|NULL|NULL||2|y|2|z|+---+---+---+---+ mysql>SELECT*FROMt1RIGHTJOINt2ON(t1.a=t2.a);+...
Does partition selection work in queries with JOIN-ed range-partitioned table? --- Here is a problem ( http://bugs.mysql.com/bug.php?id=26630 ) . Looking at EXPLAIN PARTITIONS shows that all (pruned..) partitions at joined table are accessed. And.. Some people ( http://s.pet...