how does C-sharp LINQ implement queries like left join and right join in SQL with method syntax?
how does C-sharp LINQ implement queries like left join and right join in SQL with method syntax?
..
GroupJoinright join is to write the right table on the left
//inner join
from a in StoreInCities
join b in CityInfo on a.CityId equals b.ID into c
select c
//left join (right join)
from a in StoreInCities
join b in CityInfo on a.CityId equals b.ID into c
//DefaultIfEmpty()DefaultIfEmpty()inner join
from d in c.DefaultIfEmpty()
select d
//left join
StoreInCities
.GroupJoin (
CityInfo,
a => a.CityId,
b => b.ID,
(a, c) =>
new
{
a = a,
c = c
}
)
.SelectMany (
temp0 => temp0.c.DefaultIfEmpty (),
(temp0, d) => d
)
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