有3种不同的过滤器： scale = (camera.inOrthographicMode == true)? 100 : worldPosition.distanceTo(camPosition ) / 6 * scope.size;
，books和authors（stores列表），我可以一次性使用它们，也可以只使用一次或两次他们，所以我使用UNION汇集所有查询
select如果require('database.php');
$books_ids = $authors_ids = $stores_ids = [];
if(isset($_POST['books'])){
$books_ids = $_POST["books"];
}
if(isset($_POST['authors'])){
$authors_ids = $_POST["authors"];
}
if(isset($_POST['stores'])){
$stores_ids = $_POST["stores"];
}
$query = "";
if( !empty( $books_ids ))
{
$books_ids_in = implode(',', array_fill(0, count($books_ids), '?'));
$query .= "SELECT
b.id,
b.`name`,
b.`year`,
GROUP_CONCAT(DISTINCT a.`name`) AS author_names,
GROUP_CONCAT(DISTINCT s.`name`) AS store_names,
'book' as param
FROM
books AS b
LEFT JOIN books_authors AS b_a ON b.id = b_a.book_id
LEFT JOIN authors AS a ON a.id = b_a.author_id
LEFT JOIN books_stores AS b_s ON b.id = b_s.book_id
LEFT JOIN stores AS s ON s.id = b_s.store_id
WHERE
b.id IN (". $books_ids_in .")
GROUP BY b.id";
}
if( !empty( $authors_ids ) )
{
$authors_ids_in = implode(',', array_fill(0, count($authors_ids), '?'));
if (!empty($query)) {
$query .= " UNION ";
}
$query .= "SELECT
b.id,
b.`name`,
b.`year`,
GROUP_CONCAT(DISTINCT a.`name`) AS author_names,
GROUP_CONCAT(DISTINCT s.`name`) AS store_names,
'author' as param
FROM
books AS b
LEFT JOIN books_authors AS b_a ON b.id = b_a.book_id
LEFT JOIN authors AS a ON a.id = b_a.author_id
LEFT JOIN books_stores AS b_s ON b.id = b_s.book_id
LEFT JOIN stores AS s ON s.id = b_s.store_id
WHERE
b.id IN (
SELECT DISTINCT book_id FROM books_authors WHERE author_id IN (". $authors_ids_in .")
)
GROUP BY b.id";
}
if( !empty( $stores_ids ) )
{
$stores_ids_in = implode(',', array_fill(0, count($stores_ids), '?'));
if (!empty($query)) {
$query .= " UNION ";
}
$query .= "SELECT
b.id,
b.`name`,
b.`year`,
GROUP_CONCAT(DISTINCT a.`name`) AS author_names,
GROUP_CONCAT(DISTINCT s.`name`) AS store_names,
'store' as param
FROM
books AS b
LEFT JOIN books_authors AS b_a ON b.id = b_a.book_id
LEFT JOIN authors AS a ON a.id = b_a.author_id
LEFT JOIN books_stores AS b_s ON b.id = b_s.book_id
LEFT JOIN stores AS s ON s.id = b_s.store_id
WHERE
b.id IN (
SELECT DISTINCT book_id FROM books_stores WHERE store_id IN (". $stores_ids_in .")
)
GROUP BY b.id";
}
if( !empty( $query )) {
$query .= " ORDER BY b.id";
$param_array = array_merge($books_ids, $authors_ids, $stores_ids);
$stmt = $conn->prepare($query);
$stmt->execute($param_array);
$results = $stmt->fetchAll();
echo json_encode($results);
}
$conn = null;
不为空，我会在$query末尾添加ORDER BY，如果我只使用一个过滤器，则会有效，但如果我使用2个或更多过滤器，则错误< / p>
$query .= " ORDER BY b.id";如果我尝试在Fatal error: Uncaught exception 'PDOException' with message
SQLSTATE[42000]: Syntax error or access violation: 1250 Table 'b' from one of the SELECTs cannot be used in field list' in C:\xampp\htdocs\bookstore\filter.php:102 Stack trace: #0 C:\xampp\htdocs\bookstore\filter.php(102): PDOStatement->execute(Array) #1 {main} thrown in C:\xampp\htdocs\bookstore\filter.php on line 102
ORDER BY b.id
另一个错误
$query如何在这里添加'ORDER BY'？