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Select

The select command retrieves or computes a set of values. We’ve already seen simple queries that select primitive values.

Copy
db> 
select 'hello world';
{'hello world'}
Copy
db> 
select [1, 2, 3];
{[1, 2, 3]}
Copy
db> 
select {1, 2, 3};
{1, 2, 3}

With the help of a with block, we can add filters, ordering, and pagination clauses.

Copy
db> 
... 
... 
with x := {1, 2, 3, 4, 5}
select x
filter x >= 3;
{3, 4, 5}
Copy
db> 
... 
... 
with x := {1, 2, 3, 4, 5}
select x
order by x desc;
{5, 4, 3, 2, 1}
Copy
db> 
... 
... 
with x := {1, 2, 3, 4, 5}
select x
offset 1 limit 3;
{2, 3, 4}

These queries can also be rewritten to use inline aliases, like so:

Copy
db> 
... 
select x := {1, 2, 3, 4, 5}
filter x >= 3;

However most queries are selecting objects that live in the database. For demonstration purposes, the queries below assume the following schema:

Copy
module default {
  abstract type Person {
    required name: str { constraint exclusive };
  }

  type Hero extending Person {
    secret_identity: str;
    multi villains := .<nemesis[is Villain];
  }

  type Villain extending Person {
    nemesis: Hero;
  }

  type Movie {
    required title: str { constraint exclusive };
    required release_year: int64;
    multi characters: Person;
  }
}

And the following inserts:

Copy
db> 
... 
... 
... 
insert Hero {
  name := "Spider-Man",
  secret_identity := "Peter Parker"
};
{default::Hero {id: 6be1c9c6...}}
Copy
db> 
... 
... 
... 
... 
insert Hero {
  name := "Iron Man",
  secret_identity := "Tony Stark"
};
}}
Copy
db> 
... 
... 
... 
... 
... 
for n in { "Sandman", "Electro", "Green Goblin", "Doc Ock" }
  union (
    insert Villain {
    name := n,
    nemesis := (select Hero filter .name = "Spider-Man")
 });
{
  default::Villain {id: 6c22bdf0...},
  default::Villain {id: 6c22c3d6...},
  default::Villain {id: 6c22c46c...},
  default::Villain {id: 6c22c502...},
}
Copy
db> 
... 
... 
... 
insert Villain {
  name := "Obadiah Stane",
  nemesis := (select Hero filter .name = "Iron Man")
};
{default::Villain {id: 6c42c4ec...}}
Copy
db> 
... 
... 
... 
... 
... 
insert Movie {
 title := "Spider-Man: No Way Home",
 release_year := 2021,
 characters := (select Person filter .name in
   { "Spider-Man", "Sandman", "Electro", "Green Goblin", "Doc Ock" })
 };
{default::Movie {id: 6c60c28a...}}
Copy
db> 
... 
... 
... 
... 
... 
insert Movie {
 title := "Iron Man",
 release_year := 2008,
 characters := (select Person filter .name in
  { "Iron Man", "Obadiah Stane" })
 };
{default::Movie {id: 6d1f430e...}}

Let’s start by selecting all Villain objects in the database. In this example, there are only five. Remember, Villain is a reference to the set of all Villain objects.

Copy
db> 
select Villain;
{
  default::Villain {id: 6c22bdf0...},
  default::Villain {id: 6c22c3d6...},
  default::Villain {id: 6c22c46c...},
  default::Villain {id: 6c22c502...},
  default::Villain {id: 6c42c4ec...},
}

For the sake of readability, the id values have been truncated.

By default, this only returns the id of each object. If serialized to JSON, this result would look like this:

[
  {"id": "6c22bdf0-5c03-11ee-99ff-dfaea4d947ce"},
  {"id": "6c22c3d6-5c03-11ee-99ff-734255881e5d"},
  {"id": "6c22c46c-5c03-11ee-99ff-c79f24cf638b"},
  {"id": "6c22c502-5c03-11ee-99ff-cbacc3918129"},
  {"id": "6c42c4ec-5c03-11ee-99ff-872c9906a467"}
]

Learn to select objects by trying it in our interactive object query tutorial.

To specify which properties to select, we attach a shape to Villain. A shape can be attached to any object type expression in EdgeQL.

Copy
db> 
select Villain { id, name };
{
  default::Villain {id: 6c22bdf0..., name: 'Sandman'},
  default::Villain {id: 6c22c3d6..., name: 'Electro'},
  default::Villain {id: 6c22c46c..., name: 'Green Goblin'},
  default::Villain {id: 6c22c502..., name: 'Doc Ock'},
  default::Villain {id: 6c42c4ec..., name: 'Obadiah Stane'},
}

To learn to use shapes by trying them yourself, see our interactive shapes tutorial.

Nested shapes can be used to fetch linked objects and their properties. Here we fetch all Villain objects and their nemeses.

Copy
db> 
... 
... 
... 
select Villain {
  name,
  nemesis: { name }
};
{
  default::Villain {
    name: 'Sandman',
    nemesis: default::Hero {name: 'Spider-Man'},
  },
  ...
}

In the context of EdgeQL, computed links like Hero.villains are treated identically to concrete/non-computed links like Villain.nemesis.

Copy
db> 
... 
... 
... 
select Hero {
  name,
  villains: { name }
};
{
  default::Hero {
    name: 'Spider-Man',
    villains: {
      default::Villain {name: 'Sandman'},
      default::Villain {name: 'Electro'},
      default::Villain {name: 'Green Goblin'},
      default::Villain {name: 'Doc Ock'},
    },
  },
  ...
}

Splats allow you to select all properties of a type using the asterisk (*) or all properties of the type and a single level of linked types with a double asterisk (**).

Splats will help you more easily select all properties when using the REPL. You can select all of an object’s properties using the single splat:

Copy
db> 
select Movie {*};
{
  default::Movie {
    id: 6c60c28a-5c03-11ee-99ff-dfa425012a05,
    release_year: 2021,
    title: 'Spider-Man: No Way Home',
  },
  default::Movie {
    id: 6d1f430e-5c03-11ee-99ff-e731e8da06d9,
    release_year: 2008,
    title: 'Iron Man'
  },
}

or you can select all of an object’s properties and the properties of a single level of nested objects with the double splat:

Copy
db> 
select Movie {**};
{
  default::Movie {
    id: 6c60c28a-5c03-11ee-99ff-dfa425012a05,
    release_year: 2021,
    title: 'Spider-Man: No Way Home',
    characters: {
      default::Hero {
        id: 6be1c9c6-5c03-11ee-99ff-63b1127d75f2,
        name: 'Spider-Man'
      },
      default::Villain {
        id: 6c22bdf0-5c03-11ee-99ff-dfaea4d947ce,
        name: 'Sandman'
      },
      default::Villain {
        id: 6c22c3d6-5c03-11ee-99ff-734255881e5d,
        name: 'Electro'
      },
      default::Villain {
        id: 6c22c46c-5c03-11ee-99ff-c79f24cf638b,,
        name: 'Green Goblin'
      },
      default::Villain {
        id: 6c22c502-5c03-11ee-99ff-cbacc3918129,
        name: 'Doc Ock'
      },
    },
  },
  default::Movie {
    id: 6d1f430e-5c03-11ee-99ff-e731e8da06d9,
    release_year: 2008,
    title: 'Iron Man',
    characters: {
      default::Hero {
        id: 6bf7115a-5c03-11ee-99ff-c79c07f0e2db,
        name: 'Iron Man'
      },
      default::Villain {
        id: 6c42c4ec-5c03-11ee-99ff-872c9906a467,
        name: 'Obadiah Stane'
      },
    },
  },
}

Splats are not yet supported in function bodies.

The splat expands all properties defined on the type as well as inherited properties:

Copy
db> 
select Hero {*};
{
  default::Hero {
    id: 6be1c9c6-5c03-11ee-99ff-63b1127d75f2,
    name: 'Spider-Man',
    secret_identity: 'Peter Parker'
  },
  default::Hero {
    id: 6bf7115a-5c03-11ee-99ff-c79c07f0e2db,
    name: 'Iron Man',
    secret_identity: 'Tony Stark'
  },
}

The splat here expands the heroes’ names even though the name property is not defined on the Hero type but on the Person type it extends. If we want to select heroes but get only properties defined on the Person type, we can do this instead:

Copy
db> 
select Hero {Person.*};
{
  default::Hero {
    id: 6be1c9c6-5c03-11ee-99ff-63b1127d75f2,
    name: 'Spider-Man'
  },
  default::Hero {
    id: 6bf7115a-5c03-11ee-99ff-c79c07f0e2db,
    name: 'Iron Man'
  },
}

If there are links on our Person type, we can use Person.** in a similar fashion to get all properties and one level of linked object properties, but only for links and properties that are defined on the Person type.

You can use the splat to expand properties using a type intersection. Maybe we want to select all Person objects with their names but also get any properties defined on the Hero for those Person objects which are also Hero objects:

Copy
db> 
... 
... 
... 
select Person {
  name,
  [is Hero].*
};
{
  default::Hero {
    name: 'Spider-Man',
    id: 6be1c9c6-5c03-11ee-99ff-63b1127d75f2,
    secret_identity: 'Peter Parker'
  },
  default::Hero {
    name: 'Iron Man'
    id: 6bf7115a-5c03-11ee-99ff-c79c07f0e2db,
    secret_identity: 'Tony Stark'
  },
  default::Villain {
    name: 'Sandman',
    id: 6c22bdf0-5c03-11ee-99ff-dfaea4d947ce,
    secret_identity: {}
  },
  default::Villain {
    name: 'Electro',
    id: 6c22c3d6-5c03-11ee-99ff-734255881e5d,
    secret_identity: {}
  },
  default::Villain {
    name: 'Green Goblin',
    id: 6c22c46c-5c03-11ee-99ff-c79f24cf638b,
    secret_identity: {}
  },
  default::Villain {
    name: 'Doc Ock',
    id: 6c22c502-5c03-11ee-99ff-cbacc3918129,
    secret_identity: {}
  },
  default::Villain {
    name: 'Obadiah Stane',
    id: 6c42c4ec-5c03-11ee-99ff-872c9906a467,
    secret_identity: {}
  },
}

The double splat also works with type intersection expansion to expand both properties and links on the specified type.

Copy
db> 
... 
... 
... 
select Person {
  name,
  [is Hero].**
};
{
  default::Villain {
    name: 'Sandman',
    id: 6c22bdf0-5c03-11ee-99ff-dfaea4d947ce,
    secret_identity: {},
    villains: {}
  },
  default::Villain {
    name: 'Electro',
    id: 6c22c3d6-5c03-11ee-99ff-734255881e5d,
    secret_identity: {},
    villains: {}
  },
  default::Villain {
    name: 'Green Goblin',
    id: 6c22c46c-5c03-11ee-99ff-c79f24cf638b,
    secret_identity: {},
    villains: {}
  },
  default::Villain {
    name: 'Doc Ock',
    id: 6c22c502-5c03-11ee-99ff-cbacc3918129,
    secret_identity: {},
    villains: {}
  },
  default::Villain {
    name: 'Obadiah Stane',
    id: 6c42c4ec-5c03-11ee-99ff-872c9906a467,
    secret_identity: {},
    villains: {}
  },
  default::Hero {
    name: 'Spider-Man',
    id: 6be1c9c6-5c03-11ee-99ff-63b1127d75f2,
    secret_identity: 'Peter Parker',
    villains: {
      default::Villain {
        name: 'Electro',
        id: 6c22c3d6-5c03-11ee-99ff-734255881e5d
      },
      default::Villain {
        name: 'Sandman',
        id: 6c22bdf0-5c03-11ee-99ff-dfaea4d947ce
      },
      default::Villain {
        name: 'Doc Ock',
        id: 6c22c502-5c03-11ee-99ff-cbacc3918129
      },
      default::Villain {
        name: 'Green Goblin',
        id: 6c22c46c-5c03-11ee-99ff-c79f24cf638b
      },
    },
  },
}

With this query, we get name for each Person and all the properties and one level of links on the Hero objects. We don’t get Villain objects’ nemeses because that link is not covered by our double splat which only expands Hero links. If the Villain type had properties defined on it, we wouldn’t get those with this query either.

To filter the set of selected objects, use a filter <expr> clause. The <expr> that follows the filter keyword can be any boolean expression.

To reference the name property of the Villain objects being selected, we use Villain.name.

Copy
db> 
... 
select Villain {id, name}
filter Villain.name = "Doc Ock";
{default::Villain {id: 6c22c502..., name: 'Doc Ock'}}

This query contains two occurrences of Villain. The first (outer) is passed as the argument to select and refers to the set of all Villain objects. However the inner occurrence is inside the scope of the select statement and refers to the object being selected.

However, this looks a little clunky, so EdgeQL provides a shorthand: just drop Villain entirely and simply use .name. Since we are selecting a set of Villains, it’s clear from context that .name must refer to a link/property of the Villain type. In other words, we are in the scope of the Villain type.

Copy
db> 
... 
select Villain {name}
filter .name = "Doc Ock";
{default::Villain {name: 'Doc Ock'}}

When using comparison operators like = or !=, or boolean operators and, or, and not, keep in mind that these operators will produce an empty set if an operand is an empty set. Check out our boolean cheatsheet for more info and help on how to mitigate this if you know your operands may be an empty set.

Learn to filter your queries by trying it in our interactive filters tutorial.

To filter by id, remember to cast the desired ID to uuid:

Copy
db> 
... 
select Villain {id, name}
filter .id = <uuid>"6c22c502-5c03-11ee-99ff-cbacc3918129";
{
  default::Villain {
    id: '6c22c502-5c03-11ee-99ff-cbacc3918129',
    name: 'Doc Ock'
  }
}

Filters can be added at every level of shape nesting. The query below applies a filter to both the selected Hero objects and their linked villains.

Copy
db> 
... 
... 
... 
... 
... 
select Hero {
  name,
  villains: {
    name
  } filter .name like "%O%"
} filter .name ilike "%man";
{
  default::Hero {
    name: 'Spider-Man',
    villains: {
      default::Villain {
        name: 'Doc Ock'
      }
    }
  },
  default::Hero {
    name: 'Iron Man',
    villains: {
      default::Villain {
        name: 'Obadiah Stane'
      }
    }
  },
}

Note that the scope changes inside nested shapes. When we use .name in the outer filter, it refers to the name of the hero. But when we use .name in the nested villains shape, the scope has changed to Villain.

Order the result of a query with an order by clause.

Copy
db> 
... 
select Villain { name }
order by .name;
{
  default::Villain {name: 'Doc Ock'},
  default::Villain {name: 'Electro'},
  default::Villain {name: 'Green Goblin'},
  default::Villain {name: 'Obadiah Stane'},
  default::Villain {name: 'Sandman'},
}

The expression provided to order by may be any singleton expression, primitive or otherwise.

In EdgeDB all values are orderable. Objects are compared using their id; tuples and arrays are compared element-by-element from left to right. By extension, the generic comparison operators =, <, >, etc. can be used with any two expressions of the same type.

You can also order by multiple expressions and specify the direction with an asc (default) or desc modifier.

When ordering by multiple expressions, arrays, or tuples, the leftmost expression/element is compared. If these elements are the same, the next element is used to “break the tie”, and so on. If all elements are the same, the order is not well defined.

Copy
db> 
... 
... 
... 
select Movie { title, release_year }
order by
  .release_year desc then
  str_trim(.title) desc;
{
  default::Movie {title: 'Spider-Man: No Way Home', release_year: 2021},
  ...
  default::Movie {title: 'Iron Man', release_year: 2008},
}

When ordering by multiple expressions, each expression is separated with the then keyword. For a full reference on ordering, including how empty values are handled, see Reference > Commands > Select.

Shapes can contain computed fields. These are EdgeQL expressions that are computed on the fly during the execution of the query. As with other clauses, we can use leading dot notation (e.g. .name) to refer to the properties and links of the object type currently in scope.

Copy
db> 
... 
... 
... 
select Villain {
  name,
  name_upper := str_upper(.name)
};
{
  default::Villain {
    id: 6c22bdf0...,
    name: 'Sandman',
    name_upper: 'SANDMAN',
  },
  ...
}

As with nested filters, the current scope changes inside nested shapes.

Copy
db> 
... 
... 
... 
... 
... 
... 
... 
... 
select Villain {
  id,
  name,
  name_upper := str_upper(.name),
  nemesis: {
    secret_identity,
    real_name_upper := str_upper(.secret_identity)
  }
};
{
  default::Villain {
    id: 6c22bdf0...,
    name: 'Sandman',
    name_upper: 'SANDMAN',
    nemesis: default::Hero {
      secret_identity: 'Peter Parker',
      real_name_upper: 'PETER PARKER',
    },
  },
  ...
}

There’s no limit to the complexity of computed expressions. EdgeQL is designed to be fully composable; entire queries can be embedded inside each other. Below, we use a subquery to select all movies containing a villain’s nemesis.

Copy
db> 
... 
... 
... 
... 
... 
... 
... 
select Villain {
  name,
  nemesis_name := .nemesis.name,
  movies_with_nemesis := (
    select Movie { title }
    filter Villain.nemesis in .characters
  )
};
{
  default::Villain {
    name: 'Sandman',
    nemesis_name: 'Spider-Man',
    movies_with_nemesis: {
      default::Movie {title: 'Spider-Man: No Way Home'}
    }
  },
  ...
}

All queries thus far have referenced concrete object types: Hero and Villain. However, both of these types extend the abstract type Person, from which they inherit the name property.

To learn how to leverage polymorphism in your queries, see our interactive polymorphism tutorial.

It’s possible to directly query all Person objects; the resulting set will be a mix of Hero and Villain objects (and possibly other subtypes of Person, should they be declared).

Copy
db> 
select Person { name };
{
  default::Hero {name: 'Spider-Man'},
  default::Hero {name: 'Iron Man'},
  default::Villain {name: 'Doc Ock'},
  default::Villain {name: 'Obadiah Stane'},
  ...
}

You may also encounter such “mixed sets” when querying a link that points to an abstract type (such as Movie.characters) or a union type.

Copy
db> 
... 
... 
... 
... 
... 
... 
select Movie {
  title,
  characters: {
    name
  }
}
filter .title = "Iron Man 2";
{
  default::Movie {
    title: 'Iron Man',
    characters: {
      default::Villain {name: 'Obadiah Stane'},
      default::Hero {name: 'Iron Man'}
    }
  }
}

We can fetch different properties conditional on the subtype of each object by prefixing property/link references with [is <type>]. This is known as a polymorphic query.

Copy
db> 
... 
... 
... 
... 
... 
... 
... 
select Person {
  name,
  secret_identity := [is Hero].secret_identity,
  number_of_villains := count([is Hero].villains),
  nemesis := [is Villain].nemesis {
    name
  }
};
{
  ...
  default::Villain {
    name: 'Obadiah Stane',
    secret_identity: {},
    number_of_villains: 0,
    nemesis: default::Hero {
      name: 'Iron Man'
    }
  },
  default::Hero {
    name: 'Spider-Man',
    secret_identity: 'Peter Parker',
    number_of_villains: 4,
    nemesis: {}
  },
  ...
}

This syntax might look familiar; it’s the type intersection again. In effect, this operator conditionally returns the value of the referenced field only if the object matches a particular type. If the match fails, an empty set is returned.

The line secret_identity := [is Hero].secret_identity is a bit redundant, since the computed property has the same name as the polymorphic field. In these cases, EdgeQL supports a shorthand.

Copy
db> 
... 
... 
... 
... 
... 
... 
select Person {
  name,
  [is Hero].secret_identity,
  [is Villain].nemesis: {
    name
  }
};
{
  ...
  default::Villain {
    name: 'Obadiah Stane',
    secret_identity: {},
    nemesis: default::Hero {name: 'Iron Man'}
  },
  default::Hero {
    name: 'Spider-Man',
    secret_identity: 'Peter Parker',
    nemesis: {}
  },
  ...
}

While the type of an object is displayed alongside the results of polymorphic queries run in the REPL, this is simply a convenience of the REPL and not a property that can be accessed. This is particularly noticeable if you cast an object to json, making it impossible to determine the type if the query is polymorphic. First, the result of a query as the REPL presents it with type annotations displayed:

Copy
db> 
select Person limit 1;
{default::Villain {id: 6c22bdf0-5c03-11ee-99ff-dfaea4d947ce}}

Note the type default::Villain, which is displayed for the user’s convenience but is not actually part of the data returned. This is the same query with the result cast as json to show only the data returned:

Copy
db> 
select <json>Person limit 1;
{Json("{\"id\": \"6c22bdf0-5c03-11ee-99ff-dfaea4d947ce\"}")}

We will continue to cast subesequent examples in this section to json, not because this is required for any of the functionality being demonstrated, but to remove the convenience type annotations provided by the REPL and make it easier to see what data is actually being returned by the query.

The type of an object is found inside __type__ which is a link that carries various information about the object’s type, including its name.

Copy
db> 
... 
... 
... 
... 
select <json>Person {
 __type__: {
   name
   }
 } limit 1;
{Json("{\"__type__\": {\"name\": \"default::Villain\"}}")}

This information can be pulled into the top level by assigning a name to the name property inside __type__:

Copy
db> 
select <json>Person { type := .__type__.name } limit 1;
{Json("{\"type\": \"default::Villain\"}")}

There is nothing magical about __type__; it is a simple link to an object of the type ObjectType which contains all of the possible information to know about the type of the current object. The splat operator can be used to see this object’s makeup, while the double splat operator produces too much output to show on this page. Playing around with the splat and double splat operator inside __type__ is a quick way to get some insight into the internals of EdgeDB.

Copy
db> 
select Person.__type__ {*} limit 1;
{
  schema::ObjectType {
    id: 48be3a94-5bf3-11ee-bd60-0b44b607e31d,
    name: 'default::Hero',
    internal: false,
    builtin: false,
    computed_fields: [],
    final: false,
    is_final: false,
    abstract: false,
    is_abstract: false,
    inherited_fields: [],
    from_alias: false,
    is_from_alias: false,
    expr: {},
    compound_type: false,
    is_compound_type: false,
  },
}

To select several values simultaneously, you can “bundle” them into a “free object”. Free objects are a set of key-value pairs that can contain any expression. Here, the term “free” is used to indicate that the object in question is not an instance of a particular object type; instead, it’s constructed ad hoc inside the query.

Copy
db> 
... 
... 
... 
... 
... 
select {
  my_string := "This is a string",
  my_number := 42,
  several_numbers := {1, 2, 3},
  all_heroes := Hero { name }
};
{
  {
    my_string: 'This is a string',
    my_number: 42,
    several_numbers: {1, 2, 3},
    all_heroes: {
      default::Hero {name: 'Spider-Man'},
      default::Hero {name: 'Iron Man'},
    },
  },
}

Note that the result is a singleton but each key corresponds to a set of values, which may have any cardinality.

All top-level EdgeQL statements (select, insert, update, and delete) can be prefixed with a with block. These blocks let you declare standalone expressions that can be used in your query.

Copy
db> 
... 
... 
with hero_name := "Iron Man"
select Hero { secret_identity }
filter .name = hero_name;
{default::Hero {secret_identity: 'Tony Stark'}}

For full documentation on with, see EdgeQL > With.

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