First record not shown UNION ALL - php

Question

I have the following problem.
I have a MySQL-query with UNION ALL:
$zoek = trim($_POST['zoekkey']);
$zoekstring = "%" . $zoek . "%";
$stmtsk = $user_home->runQuery(
"(SELECT city_zip, city_name, tp_status, tp_city as city, themepark_id as id, tp_logo as logo, tp_name as name, tp_address as address, 'Uitstap' as categorie FROM themepark "
. "INNER JOIN city ON themepark.tp_city=city.city_id "
. "WHERE (tp_name LIKE :search OR tp_address LIKE :search) AND tp_status = 1) "
. "UNION ALL "
. "(SELECT city_zip, city_name, hot_status, hot_city as city, hotel_id as id, hot_logo as logo, hot_name as name, hot_address as address, 'Overnachten' as categorie FROM hotel "
. "INNER JOIN city ON hotel.hot_city=city.city_id "
. "WHERE (hot_address LIKE :search OR hot_name LIKE :search) AND hot_status = 1) "
. "UNION ALL "
. "(SELECT city_zip, city_name, rest_status, rest_city as city, restaurant_id as id, rest_logo as logo, rest_name_".$_SESSION['lang']." as name, rest_address as address, 'Restaurant' as categorie FROM restaurant "
. "INNER JOIN city ON restaurant.rest_city=city.city_id "
. "WHERE (rest_address LIKE :search OR rest_name_".$_SESSION['lang']." LIKE :search) AND rest_status = 1) "
. "UNION ALL "
. "(SELECT city_zip, city_name, sbs_status, sbs_city as city, sbs_id as id, sbs_logo as logo, sbs_name as name, sbs_address as address, 'Detailhandel' as categorie FROM sbs " //detailhandel
. "INNER JOIN city ON sbs.sbs_city=city.city_id "
. "WHERE (sbs_address LIKE :search OR sbs_name LIKE :search) AND sbs_status = 1 AND sbs_categorie = 'detail') "
. "UNION ALL "
. "(SELECT city_zip, city_name, sbs_status, sbs_city as city, sbs_id as id, sbs_logo as logo, sbs_name as name, sbs_address as address, 'Horeca' as categorie FROM sbs " //horeca
. "INNER JOIN city ON sbs.sbs_city=city.city_id "
. "WHERE (sbs_address LIKE :search OR sbs_name LIKE :search) AND sbs_status = 1 AND sbs_categorie = 'horeca')
`ORDER BY categorie,name`"
);
$stmtsk->bindParam(":search",$zoekstring);
$stmtsk->execute();
$rowsk = $stmtsk->fetch(PDO::FETCH_ASSOC);
The strange thing is, the first row off the result is not coming up.
All the others are OK.
When I run the same query in PHPMyAdmin it is working fine...
I really don't understand why it isn't showing it.
Thanks in advance!

Answer 1

Very unlikely it's a problem with the query. But we can't entirely rule out an issue with the LIKE comparisons and a characterset difference. And we can't rule out issues with the values being supplied for the bind parameters,
We're just guessing. But the most likely explanation for the observed behavior is that the code is fetching the first row, and then doing nothing with it, and then fetching the next row. We could reproduce the reported behavior with a code pattern like this:
$sth->execute();
$row = $sth->fetch();
// do nothing with the row we just fetched
while( $row = $sth->fetch() ) {
// fetch another row and output it
}
This pattern would explain why we don't "get" the first row. (We actually get the row, we just ignore it, and fetch the next row.
Other thoughts:
Without an ORDER BY clause, the database can return rows in any order. So what is the "first" row with one execution could be the third row, or last row, on subsequent executions.
If the issue was with particular rows (values) not being returned, other than just the reported "missing first row", that would likely be due to conditions in the WHERE clause, how the query is evaluated. But that issue could affect more than just the one "first" row.