PDO在SELECT语句后返回错误的rowCount() [英] PDO returns wrong rowCount() after SELECT statement

问题描述

我正在执行与此类似的代码:

Im executing code similar to this:

// first select
$query = $link->prepare("
            SELECT id FROM table
            WHERE name = ?;"); 

$param = 'foo';

$query->bindParam(1, $param); // should return 1 row
$query->execute();
echo $query->rowCount(); // displays 0 (??????)

其他示例:

// second select
$query = $link->prepare("
            SELECT id FROM table
            WHERE name = ?;"); // should return 0 rows

$param = 'bar';

$query->bindParam(1, $param);
$query->execute();
echo $query->rowCount(); // displays 1 (?????)

我的桌子:

id | name
---------
1  | foo

我不明白.

推荐答案

某些数据库可能返回SELECT语句返回的行数.但是，并非所有数据库都可以保证有此行为，因此不应该依赖此行为. 手册 可以在以下查询中使用COUNT(*)和fetchColumn()来模拟rowCount().

Some databases may return the number of rows returned by a SELECT statement. However, this behaviour is not guaranteed for all databases and should not be relied on .Manual You can use COUNT(*) and fetchColumn() as in following query to emulate rowCount().

$query = $link->prepare("SELECT COUNT(*) FROM table  WHERE name = ?");
$param = 'bar';
$query->bindParam(1,$param);
$query->execute();
// Check the number of rows that match the SELECT statement 
if($query->fetchColumn() == 0) {
    echo "No records found";
 }else{
        $query = $link->prepare("SELECT id FROM table WHERE name = ?")
        //Etc
}

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