[英]C# linq lambda join and select syntax
我正在尋找Msql查詢的對應物:
SELECT per.*,add.addressDescription FROM Persons per
JOIN Address add ON per.AddressId = add.AddressId
我有這個問題:
var query = persons.JOIN(address,per = person.addressId,add = addressId
(per,add) =>
new Persons{
addressDescription = add.addressDescription,
PersonId = per.PersonId,
PersonFirstName = per.PersonFirstName
PersonLastName = per.PersonLastName})
有沒有一種方法來填充Persons.addressDescription
不單獨分配的其他財產Persons
? 想象一下,如果Persons
還有10個屬性。
我想不要使用如下循環:
foreach(Person person in PersonList)
{
foreach(Address address in AddressList)
{
if(person.addressId == address.addressId){
person.addressDescription = address.addressDescription
}
}
}
var query = persons.join(address,
per = person.addressId,
add = addressId
(per,add) =>
{
per.addressDescription = add.addressDescription;
return per;
});
var id = 1;
var query = database.Posts // your starting point - table in the "from" statement
.Join(database.Post_Metas, // the source table of the inner join
post => post.ID, // Select the primary key (the first part of the "on" clause in an sql "join" statement)
meta => meta.Post_ID, // Select the foreign key (the second part of the "on" clause)
(post, meta) => new { Post = post, Meta = meta }) // selection
.Where(postAndMeta => postAndMeta.Post.ID == id); // where statement
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