SQL 错误代码：1054。未知列
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Error Code: 1054. Unknown column
提问by David
I have the following SQL statement:
我有以下 SQL 语句：
SELECT efforts.user_id, project_tasks.task_name, sum(hours)
FROM efforts, users, project_tasks
INNER JOIN PROJECT_TASKS pu ON efforts.project_task_id = pu.id
INNER JOIN USERS u ON efforts.users_id = u.id
WHERE project_tasks.project_id = '2';
And when I run it I get the following error:
当我运行它时，我收到以下错误：
Error Code: 1054. Unknown column 'efforts.project_task_id' in 'on clause'
Why am I getting this error?
为什么我收到这个错误？
Project_task_id belongs to efforts table
project_task_id 属于努力表
Updated:
更新：
SELECT u.full_name, pu.task_name, hours
FROM efforts
INNER JOIN project_tasks pu ON efforts.project_task_id = pu.id
INNER JOIN users u ON efforts.user_id = u.id
GROUP BY user_id, task_name
回答by StevieG
Your syntax is wrong, it should be:
你的语法错误，应该是：
SELECT efforts.user_id, pu.task_name, sum(hours)
FROM efforts
INNER JOIN PROJECT_TASKS pu ON efforts.project_task_id = pu.id
INNER JOIN USERS u ON efforts.user_id = u.id
WHERE pu.project_id = '2';
回答by Lukas Eder
Note that as far as I know, MySQL is case-sensitive on table names (not on column names)... That might cause some trouble in your query...? Along with StevieG's correction
请注意，据我所知，MySQL 对表名（而不是列名）区分大小写...这可能会在您的查询中造成一些麻烦...？随着 StevieG 的更正
