MySQL包含計數不返回計數為零的行

Question

我有以下MySQL代碼：

SELECT COUNT(e.eid) AS cnt, e.c_id, c.cdesc 
FROM e 
JOIN c on c.c_id = e.c_id 
GROUP by c.c_id

不幸的是，該count未考慮到0行，因此例如c_id可能有10行，但僅顯示9行（因為e_id的計數之一為零）。

我嘗試了LEFT JOIN和RIGHT JOIN沒有成功。 還有其他建議嗎？

Answer 1

我懷疑您需要的是：

SELECT COUNT(*) AS cnt, c.c_id, c.cdesc 
FROM c 
LEFT JOIN e on c.c_id = e.c_id 
GROUP by c.c_id

Answer 2

SELECT COUNT(e.eid) AS cnt, e.c_id, c.cdesc 
FROM c
left JOIN e on c.c_id = e.c_id 
GROUP by c.c_id

Answer 3

采用：

SELECT COUNT(*) AS cnt, e.c_id, c.cdesc 
FROM e 
JOIN c on c.c_id = e.c_id 
GROUP by c.c_id