使用查询num_row（）得到-1的PHP代码Igniter

Question

Im using below code to get result from database. Im expecting to get row count > 0 because I have 1 entry in database. Instead I'm getting the result below.

-1Array
(
    [0] => stdClass Object
        (
            [lngID] => 1
            [strRefTable] => team
            [intFirstParent] => 
            [intSecondParent] => 
            [bitHasChild] => 
            [strRefValue] => Automation
            [strShortDesc] => Automation
            [strLongDesc] => Automation
            [strCreatedBy] => 181551
            [dteCreatedDate] => 2019-03-27 09:09:08.000
            [strUpdatedBy] => 181551
            [dteUpdatedDate] => 2019-03-27 09:09:08.000
            [bitActive] => 1
        )

)

Where -1 represents the echo of $query->num_rows() and the array proves that I have record in database.

$query = $db->query($sql);
if(!$query) {
throw new Exception('Server error');
}
echo $query->num_rows();exit();
print_r($query->result());die();
if($query->num_rows() > 0){
$result = $query->result();
} 

Why do I get -1 as row count?

UPDATE

Using MSSQL

Answer 1

One possible explanation for this behavior (if you use PDO PHP Driver for SQL Server to connect to SQL Server), is that num_rows() uses PDOStatement::rowCount and based on documentation, the result will be -1 if you execute SELECT statement and do not use approipriate cursor type.

Returns the number of rows added, deleted, or changed. If the last SQL statement executed by the associated PDOStatement was a SELECT statement, a PDO::CURSOR_FWDONLY cursor returns -1. A PDO::CURSOR_SCROLL ABLE cursor returns the number of rows in the result set.