Trait diesel::pg::expression::extensions::OnlyDsl
source · pub trait OnlyDsl: Table {
// Provided method
fn only(self) -> Only<Self> { ... }
}
Expand description
The only
method
This is only implemented for the Postgres backend.
The ONLY
clause is used to select only from one table and not any inherited ones.
Calling this function on a table (mytable.only()
) will result in the SQL ONLY mytable
.
mytable.only()
can be used just like any table in diesel since it implements
Table.
Example:
let n_sers_in_main_table = users::table
.only()
.select(count(users::id))
.first::<i64>(connection);
Selects the number of entries in the users
table excluding any rows found in inherited
tables.
It can also be used in inner joins:
users::table
.inner_join(posts::table.only())
.select((users::name, posts::title))
.load::<(String, String)>(connection);
That query excludes any posts that reside in any inherited table.
Provided Methods§
Object Safety§
This trait is not object safe.