实体框架:连接两个表和where子句
实体框架:连接两个表和where子句
提问于 2021-05-14 20:56:22
我在使用实体框架和PostgreSQL时遇到了问题，有谁知道如何连接两个表并将第二个表用作where子句？
我希望在Entity Framework中执行的select操作将使用SQL：
SELECT ai.id, ai.title, ai.description, ai.coverimageurl
FROM app_information ai
INNER JOIN app_languages al on al.id = ai.languageid
WHERE al.languagecode = 'es'目前我有这个
appInformationToReturn = context.app_information
.Join(context.app_language, ai => ai.languageid,
al => al.id, (ai, al) => new AppInformation()
{
id = ai.id,
title = ai.title,
description = ai.description,
coverimageurl = ai.coverimageurl
})
.Where()
.FirstOrDefault();我不知道如何构建where子句。
回答 2
Stack Overflow用户
回答已采纳
发布于 2021-05-15 00:02:20
如下所示：
appInformationToReturn = context.app_information
.Join(context.app_language, ai => ai.languageid,
al => al.id, (ai, al) => new
{
id = ai.id,
title = ai.title,
description = ai.description,
coverimageurl = ai.coverimageurl,
lang = al.languagecode
}).Where(x=>x.lang == "es")
.Select(x=> new AppInformation()
{
id = x.id,
title = x.title,
description = x.description,
coverimageurl = x.coverimageurl
})
.FirstOrDefault();Stack Overflow用户
发布于 2021-05-14 21:23:45
试试这个：
var item = (
from ai in context.app_information
join al in context.app_language on ai.languageid equals al.id
where (al.languagecode == "es")
select new AppInformation
{
id = ai.id,
title = ai.title,
description = ai.description,
coverimageurl = ai.coverimageurl
}).FirstOrDefault();或者尝试更短
var item = context.app_information
.Where(ai => ai.app_language.languagecode == "es")
.Select(ai => new AppInformation
{
id = ai.id,
title = ai.title,
description = ai.description,
coverimageurl = ai.coverimageurl
})
.FirstOrDefault();页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/67534732
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