Php 选择带有内部联接的计数
我有两张桌子:Php 选择带有内部联接的计数,php,mysql,Php,Mysql,我有两张桌子: project (id, name) list (id, name, project_id) 我想把每一个项目和清单的数量都加入到这个项目中 我试过: SELECT project.id, project.name, COUNT(list.id) AS list_count FROM project INNER JOIN list ON (list.project_id = project.id) GROUP BY project.id DESC 但我只得到有列表的项目 如
project (id, name)
list (id, name, project_id)
我想把每一个项目和清单的数量都加入到这个项目中
我试过:
SELECT project.id, project.name, COUNT(list.id) AS list_count
FROM project
INNER JOIN list ON (list.project_id = project.id)
GROUP BY project.id DESC
但我只得到有列表的项目
如果项目没有自己的列表,我就不明白
如果count(list\u id)=0,我想要list\u count=0,我必须怎么做?请使用左连接而不是内部连接
SELECT project.id, project.name, COUNT(list.id) AS list_count
FROM project
Left JOIN list ON (list.project_id = project.id)
GROUP BY project.id DESC
使用左联接而不是内联接
SELECT project.id, project.name, COUNT(list.id) AS list_count
FROM project
Left JOIN list ON (list.project_id = project.id)
GROUP BY project.id DESC