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我有兩個數據庫表:如何列出未完成任務的組和計數?
tasks:
task_id (unique id, autoincrement)
group_id (from the next table: groups, where task belongs to)
task_name
status (if task has been completed or not)
groups:
group_id (unique id, autoincrement)
group_name
我的目標是列出所有組,在他們未完成任務數(任務狀態0)一起。 我實現,通過這個查詢:
$sql_query = "SELECT g.id, g.name, count(g.id) as count
FROM task_groups g, tasks t
WHERE g.status = 0 AND t.group = g.id AND t.status = 0
GROUP BY g.id
ORDER BY g.id ASC";
而我得到的結果是這樣的:
Group1 3 uncompleted Group2 13 uncompleted Group3 30 uncompleted
但空任務組(沒有屬於特定組的任何任務)沒有被列出。
結果應該是這樣的:
Group1 3 uncompleted Group2 13 uncompleted Group3 30 uncompleted Group4 0 uncompleted Group5 0 uncompleted
我怎樣才能做到這一點?
這就是所需的解決方案。順便說一下g.status在這裏沒有關係,所以你沒有理由忽略它。 – Spec 2011-12-16 23:52:22