mysqli_num_rows总是在PHP中显示1（工作台显示OK）

Question

我有以下代码来显示表中记录的数字，即使我将列名更改为另一个列名，它也总是显示1;

然而，工作台中的相同查询显示正确的记录数。见截图;

$con = @mysqli_connect( "localhost:3306", "root", "P@ssw0rd", "classicmodels" ) or die ("Couldn't connect to server");
    //get total number of records
    $query = "SELECT count(checkNumber) FROM payments";
    $result = mysqli_query ( $con, $query) or die ("Couldn't execute SELECT query: ". mysqli_error($con));
    $rec_count = mysqli_num_rows($result);

    echo $rec_count."<br>";

Answer 1

这是因为num_rows显示您获取的行数，在这种情况下，只有一行。您应该从数据库中获取count(checkNumber)字段，其中包含行数，而不是num_rows函数。

将它计为变量更好，例如COUNT(someField) as FieldCount

Answer 2

结果中只会有一行。您应该获取记录然后回显$ record [＆＃39; count（checkNumber）＆＃39;]。 （别名会使索引更直观）。

Answer 3

您在查询中使用count函数，它将在一行中给出答案。要使用获得正确的答案，您可以删除count（）并保持其余代码相同。请参阅以下代码。

  $con = @mysqli_connect( "localhost:3306", "root", "P@ssw0rd", "classicmodels" ) or die ("Couldn't connect to server");
//get total number of records
//I have Removed COUNT() from query
$query = "SELECT checkNumber FROM payments";
$result = mysqli_query ( $con, $query) or die ("Couldn't execute SELECT query: ". mysqli_error($con));
$rec_count = mysqli_num_rows($result);

echo $rec_count."<br>";

OR

您可以使用count（）函数并获得正确的答案。

$con = @mysqli_connect( "localhost:3306", "root", "P@ssw0rd", "classicmodels" ) or die ("Couldn't connect to server");
//get total number of records
$query = "SELECT count(checkNumber) FROM payments";
$result = mysqli_query ( $con, $query) or die ("Couldn't execute SELECT query: ". mysqli_error($con));
while($rec_row = mysqli_fetch_row($result))
{
    $rec_count=$rec_row['count(checkNumber)'];
}

echo $rec_count."<br>";