EdgeQL supports a top-level for statement. These “for loops” iterate over
each element of some input set, execute some expression with it, and merge the
results into a single output set.
db> ... ... ...
for number in {0, 1, 2, 3}
union (
select { number, number + 0.5 }
);{0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5}This statement iterates through each number in the set. Inside the loop, the
number variable is bound to a singleton set. The inner expression is
executed for every element of the input set, and the results of each execution
are merged into a single output set.
The union keyword is a required part of the for statement syntax; it
is intended to indicate explicitly that the results of each loop execution
are ultimately merged.
The for statement is commonly used for bulk inserts.
db> ... ... ...
for hero_name in {'Cersi', 'Ikaris', 'Thena'}
union (
insert Hero { name := hero_name }
);{
default::Hero {id: d7d7e0f6-40ae-11ec-87b1-3f06bed494b9},
default::Hero {id: d7d7f870-40ae-11ec-87b1-f712a4efc3a5},
default::Hero {id: d7d7f8c0-40ae-11ec-87b1-6b8685d56610}
}This statement iterates through each name in the list of names. Inside the
loop, hero_name is bound to a str singleton, so it can be assigned to
Hero.name.
Instead of literal sets, it’s common to use a json
parameter for bulk inserts. This value is then “unpacked” into a set of
json elements and used inside the for loop:
db> ... ... ... ...
with
raw_data := <json>$data,
for item in json_array_unpack(raw_data) union (
insert Hero { name := <str>item['name'] }
);Parameter <json>$data: [{"name":"Sersi"},{"name":"Ikaris"},{"name":"Thena"}]
{
default::Hero {id: d7d7e0f6-40ae-11ec-87b1-3f06bed494b9},
default::Hero {id: d7d7f870-40ae-11ec-87b1-f712a4efc3a5},
default::Hero {id: d7d7f8c0-40ae-11ec-87b1-6b8685d56610}
}A similar approach can be used for bulk updates.
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