Description:
------------
Using lastInsertId with PgSQL just returns the OID which is not what we want.

As all the tables are using sequences I thought I may as well get the currval of their sequence in the primary key field.

Ran these queries through phpPgAdmin and it returns currval row with a value, but through PDO it returns nothing.

I started using a simple PDO::query() call and then moved it into a full prepare/execute call.

Reproduce code:
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$sql = "INSERT INTO table (bah, foo) VALUE ('woo', 'waz)";
$statement = $this->db->prepare($sql);
if (!$statement->execute()) {
    throw new Exception("Failed query [$sql] with error [" . $this->db->errorInfo() . "]");
}

$sql = "SELECT currval('".strtolower($idnr_seq)."')";
$stmt = $this->db->prepare($sql);
if (!$statement->execute()) {
    throw new Exception("Failed query [$sql] with error [" . $this->db->errorInfo() . "]");
}

print_r($stmt->fetch(PDO_FETCH_ASSOC));

Expected result:
----------------
Array ( [currval] => '27' )

Actual result:
--------------
Array ( [currval] => )