PDO-获得COUNT(*)的结果? [英] PDO - get the result of a COUNT(*)?

问题描述

在新的用户注册过程中，我正在尝试查找数据库中是否已存在用户名或用户电子邮件.为此，我想查找标识符(电子邮件或用户名)与数据库中的记录匹配的行数.如果我不搞清楚，唯一的可能返回值是0或1.我的函数在下面，但我需要帮助来完成它.

During the new user registration process, I'm trying to find whether a user name or a user email are already in the db. To do that, I want to find the number of rows where the identifier (email or user name) matches records in the database. If I don't screw up, the only possible return values are 0 or 1. My function is below, but I need help to complete it.

function checkUserExists($userIdentifier, $tableColName){
 $dbConnection=$this->dbInstance->createConnexion();
 $query=$dbConnection->prepare("SELECT count(*) FROM users WHERE ".$tableColName."= :userIdentifier");
 $query->bindParam(":userIdentifier", $userIdentifier);
 $result=$query->execute();
 if( ????? >0){
  $return false;
 } else return true;
}

我很傻，我不确定如何获得该计数.我想这是$query->fetch()的某种变体，但这将是一个数组吗?

Silly of me, I'm not sure how to get that count number. I suppose it's some variation of $query->fetch(), but that's going to be an array right?

推荐答案

您可以使用 ->fetchColumn(0) 从下一个(唯一的)行集中获取唯一的1列.

You could use ->fetchColumn(0) to get the 1 and only column from the next (one and only) rowset.

if ( $query->fetchColumn(0) > 0 ){
  return false;
} else return true;

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