mysql - 查询结果减1

Question

SELECT count(P.pID)
FROM Department D, Professor P
WHERE D.dID = ? AND P.dID = D.dID;

我想从 count(P.pID) 的任何结果中减去“1”。因此，例如，如果 P.pID 的值为 10，它将输出 9... ??

Answer 1

SELECT count(P.pID) - 1 as pID_count 
FROM Department D, Professor P 
WHERE D.dID = ? AND P.dID = D.dID;