是否可以在同一查询中计算两列

Question

假设我具有以下表格结构：

t1
-------------
id // row id
userID_follower // this user is a follows another member
userID_following  // other member that this user

是否可以运行单个查询以结合以下两个条件：

1. 此人正在关注多少用户

从t1 WHERE userID_follower =“。$ myID”中选择COUNT（id）。。”

1. 有多少用户关注此人

从t1 WHERE userID_following =“。$ myID”中选择COUNT（id）。

谢谢。

Answer 1

在MySql中，您可以SUM()在条件上使用该函数，因为错误条件将等于0，而真正条件将等于1：

SELECT SUM(userID_follower = $myID) AS followerCount,
   SUM(userID_following = $myID) AS followingCount
FROM t1
WHERE userID_follower = $myID
   OR userID_following = $myID