为什么fetchColumn（）在有2列时返回1？

为什么fetchColumn()在数据库中实际存在两列符合这些条件时会返回“1”？为什么fetchColumn（）在有2列时返回1？

如果数据库中有1条记录匹配，它将返回false？（我以前做$num_of_rows = $stmt->num_rows()它完美地工作）

$follower = 1; 
$following = 1; 

$stmt = $dbCon->prepare(" SELECT login_followers_status " 
     . " FROM login_followers " 
     . " WHERE login_followers_follower = ? " 
     . " AND login_followers_following = ? "); 
$stmt->bindParam(1, $follower); 
$stmt->bindParam(2, $following); 
$stmt->execute(); 
$row = $stmt->fetch(); 
$status = $row['login_followers_status']; 
$num_of_rows = $stmt->fetchColumn(); 

echo $num_of_rows;

来源

2017-08-08 Javaish