PHP PDO - 行数 [英] PHP PDO - Num Rows

问题描述

PDO 显然无法计算从选择查询返回的行数(mysqli 有 num_rows 变量).

PDO apparently has no means to count the number of rows returned from a select query (mysqli has the num_rows variable).

除了使用 count($results->fetchAll()) 之外，有没有办法做到这一点?

Is there a way to do this, short of using count($results->fetchAll()) ?

推荐答案

根据手册，有一个PDOStatement->rowCount 方法；但不应该使用它(quoting) :

According to the manual, there is a PDOStatement->rowCount method ; but it shouldn't be used (quoting) :

对于大多数数据库，PDOStatement::rowCount() 没有返回受影响的行数SELECT 语句.
相反，使用PDO::query() 发出一个 SELECT COUNT(*) 语句谓词作为您的预期 SELECT声明，然后使用PDOStatement::fetchColumn() 到检索将要执行的行数被退回.
然后您的应用程序可以执行正确的操作.

For most databases, PDOStatement::rowCount() does not return the number of rows affected by a SELECT statement.
Instead, use PDO::query() to issue a SELECT COUNT(*) statement with the same predicates as your intended SELECT statement, then use PDOStatement::fetchColumn() to retrieve the number of rows that will be returned.
Your application can then perform the correct action.

如果您已经有一个记录集，并且想知道其中有多少行，则必须使用 fetch* 方法之一来获取数据；并使用计数——就像你建议的那样.

If you already have a recordset, and want to know how many lines are in it, you'll have to fetch the data, using one of the fetch* methods ; and use count -- like you suggested.

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