作为连接的结果获取PHP MySQL PDO列表名

Question

I have fields that have the same name in different tables that I'm joining. Such as ticket.status , user.status and transaction.status . At the moment the query returns just status .

How can I get the table name in such a way that it stops similar field names from overwriting and so I can tell the difference between the fields.

Simply put:

$data = array($eventId);
$statement = $this->db->prepare("SELECT * FROM ticket, user, transaction 
                        WHERE ticket.eventId = ? 
                        AND ticket.userId = user.userId
                        AND ticket.transactionId = transaction.transactionId");

$statement->execute($data); 
$rows = $statement->fetchAll(PDO::FETCH_ASSOC);

In my research I've found the constant PDO::ATTR_FETCH_TABLE_NAMES that looks like it could help, but I do not know how to implement ( I assume through $statement->setAttribute(); somehow).

I also have concerns that it will not work, as the PHP documentation mentions it is dependent on the driver.

Thanks

Answer 1

Just add new aliases to your select statements

$statement = $this->db->prepare("
    SELECT *, ticket.status AS ticket_status, user.status AS user_status, transaction.status AS transaction_status 
    FROM ticket, user, transaction 
    WHERE ticket.eventId = ? 
    AND ticket.userId = user.userId
    AND ticket.transactionId = transaction.transactionId
");

Then you can do

$rows[0]['user_status'];
$rows[0]['ticket_status'];
$rows[0]['transaction_status'];

If you are really concern by performance, the quantity of data returned will be greater so instead of adding new aliases you can select every single columns and while you do so put an alias on the status column.

Answer 2

Why not change your to actually join instead:

SELECT 
t.status as ticket_status, u.status as user_status, tr.status as trans_status
FROM 
ticket as t
inner join user as u on t.userId = u.userId
inner join transaction as tr on t.transactionId = tr.transactionId
where
t.eventId = ?

You don't even need to cast the tables using as something but I find it's neater.

Note, its the casting of the columns that will actually fix this issue, not the join method.

Answer 3

The most obvious comment is "don't do it, that's why aliases exist". But there's still a good underlying question: does MySQL send information about where a result-set column comes from (table, view or calculated)?

Apparently, it does, since the PDOStatement object has an experimental method called getColumnMeta() . I've been testing and it returns an associative array where the table key

• contains the source table if column comes from a table or view
• is an empty string if the column is calculated

Of course, I'd stick to aliases anyway. Being able to use associative arrays is a killer feature for me.