MyCATApache/Mycat-Server

基于catlet的多表join怎么实现呢？

Open

#2,674 opened on Dec 8, 2020

View on GitHub
 (1 comment) (0 reactions) (0 assignees)Java (3,886 forks)batch import
help wanted

Repository metrics

Stars
 (9,451 stars)
PR merge metrics
 (No merged PRs in 30d)

Description

我在mysql中能够实现三表join查询，但是在mycat中/*!mycat:catlet=io.mycat.catlets.ShareJoin */select * from (student s join student_info i on s.student_id=i.student_id) join class_info c on s.student_id = c.class_id;报空指针异常错误。

Contributor guide

Research direction
Inspect the ShareJoin catlet source code in Mycat Server to find the null pointer exception when handling multi table joins with parentheses. Trace the execution path of the query and identify the missing null check.
Tech stack
java
Domain
backenddatabase
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaMySQLMycat
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60