Question

我遇到了jpa查询的问题：

SELECT DISTINCT p FROM Product p INNER JOIN p.shopCategories sc WHERE EXISTS (SELECT DISTINCT sc2 FROM Customer c INNER JOIN c.shopCategories as sc2 WHERE c.customerId=7)

结果应该只是具有商店类别的页面，其中客户已经预订了该商店类别。

产品＆lt; - ＆gt; ShopCategory＆lt; - ＆gt;客户

但结果是包含任何ShopCategory存在的所有产品的列表。

如何改进查询？

Answer 1

我会一直加入客户

[DataContract]
public class Request
{
    [DataMember]
    public Child Child { get; set; }
}

[DataContract]
public class Child
{
    [DataMember]
    public CountryISO CountryISO { get; set; }
}

[DataContract]
public class CountryISO
{
    [DataMember]
    [XmlElement("country")]
    public List<string> country { get; set; }
}

如果您的ShopCategories实体当然有双向映射。

<强>更新

使用EXISTS，我认为你需要将内部查询与父查询相关联：

from circuits.web.client import Client, request as request_event
from circuits.web import Server, Controller
from circuits import handler


class Root(Controller):

    @handler('request')
    def _on_request(self):

        a = yield self.wait(request_event('GET', 'https://www.w3.org/services/html2txt?url=http%3A%2F%2Fwww.example.com%2F'), channel='url-fetching')
        b = yield self.wait((request_event('GET', 'http://home.hiwaay.net/~jimes/checklist.txt'), channel='url-fetching')

        self.response.headers["Content-Type"] = "text/plain"
        self.response.body = "%s %s" % (a.value.read(), b.value.read())


(Server(('0.0.0.0', 8011)) + Root() + Client(channel='url-fetching').run()

JPA存在/加入的地方

1 个答案: