我有一个oc_category_description表,其中各列是:
和其他表oc_category,其中列是:
这里我要选择全名为tbl_cat_desc的行,其中tbl_cat parent_id为0;
这里是sql:
$stmt = $this->con->prepare("SELECT category_id, image, parent_id, (SELECT oc_category_description.name FROM oc_category_description WHERE oc_category.category_id = oc_category_description.category_id) FROM oc_category WHERE parent_id = 0 ORDER BY category_id ASC");
但不返回任何内容:(
使用加入
SELECT ocd.category_id, image, parent_id, name
FROM oc_category_description AS ocd
INNER JOIN oc_category
WHERE parent_id = 0
ORDER BY ocd.category_id ASC
[使用内部联接:
SELECT d.category_id, d.image, c.parent_id, d.name
FROM oc_category_description d INNER JOIN oc_category c
ON c.category_id = d.category_id
WHERE c.parent_id = 0
ORDER BY d.category_id