##Instruction:
Database: superhero
Total Tables: 10
Total Columns: 31

Table Schemas:

Database: superhero
Total Tables: 10
Total Columns: 31

Table Schemas:

Table: alignment (2 columns)
----------------------------
• id (integer): the unique identifier of the alignment
• alignment (text): the alignment of the superhero
  Values: commonsense evidence:
Alignment refers to a character's moral and ethical stance and can be used to ...

Table: attribute (2 columns)
----------------------------
• id (integer): the unique identifier of the attribute
• attribute_name (text): the attribute
  Values: commonsense evidence:
A superhero's attribute is a characteristic or quality that defines who they a...

Table: colour (2 columns)
-------------------------
• id (integer): the unique identifier of the color
• colour (text): the color of the superhero's skin/eye/hair/etc

Table: gender (2 columns)
-------------------------
• id (integer): the unique identifier of the gender
• gender (text): the gender of the superhero

Table: hero_attribute (3 columns)
---------------------------------
• hero_id: the id of the hero
Maps to superhero(id)
• attribute_id: the id of the attribute
Maps to attribute(id)
• attribute_value: the attribute value
  Values: commonsense evidence:
If a superhero has a higher attribute value on a particular attribute, it mean...

Table: hero_power (2 columns)
-----------------------------
• hero_id (integer): the id of the hero
Maps to superhero(id)
• power_id (integer): the id of the power
Maps to superpower(id)
  Values: commonsense evidence:
In general, a superhero's attributes provide the foundation for their abilitie...

Table: publisher (2 columns)
----------------------------
• id (integer): the unique identifier of the publisher
• publisher_name (text): the name of the publisher

Table: race (2 columns)
-----------------------
• id (integer): the unique identifier of the race
• race (text): the race of the superhero
  Values: commonsense evidence:
In the context of superheroes, a superhero's race would refer to the particula...

Table: superhero (12 columns)
-----------------------------
• id (integer): the unique identifier of the superhero
• superhero_name (text): the name of the superhero
• full_name (text): the full name of the superhero
  Values: commonsense evidence:
The full name of a person typically consists of their given name, also known a...
• gender_id (integer): the id of the superhero's gender
• eye_colour_id (integer): the id of the superhero's eye color
• hair_colour_id (integer): the id of the superhero's hair color
• skin_colour_id (integer): the id of the superhero's skin color
• race_id (integer): the id of the superhero's race
• publisher_id (integer): the id of the publisher
• alignment_id (integer): the id of the superhero's alignment
• height_cm (integer): the height of the superhero
  Values: commonsense evidence:
The unit of height is centimeter. If the height_cm is NULL or 0, it means the ...
• weight_kg (integer): the weight of the superhero
  Values: commonsense evidence:
The unit of weight is kilogram. If the weight_kg is NULL or 0, it means the we...

Table: superpower (2 columns)
-----------------------------
• id (integer): the unique identifier of the superpower
• power_name (text): the superpower name

##Evidence:
no skin colour refers to skin_colour_id = 1 where colour is 'No Colour'; proportion is calculated as the number of superheroes with no skin colour divided by the total number of superheroes.

##Role Access Policy (Column-Level):
Role: DataOperator_3
Accessible Columns: alignment: ALL COLUMNS; attribute: ALL COLUMNS; colour: ALL COLUMNS; gender: ALL COLUMNS; race: ALL COLUMNS; superhero: ALL COLUMNS; superpower: ALL COLUMNS

Based on the above schema and your role's column-level access policy, generate a SQL query to answer the question. If your role does not have access to the required columns, respond with: "Sorry, I cannot answer."


Question: What is the proportion of superheroes with no skin colour?
Evidence: no skin colour refers to skin_colour_id = 1 where colour is 'No Colour'; proportion is calculated as the number of superheroes with no skin colour divided by the total number of superheroes.
Answer: SELECT CAST(SUM(CASE WHEN skin_colour_id = 1 THEN 1 ELSE 0 END) AS REAL) / COUNT(*) FROM superhero
Permission: allowed (All required columns are permitted)
Gold SQL: SELECT CAST(SUM(CASE WHEN skin_colour_id = 1 THEN 1 ELSE 0 END) AS REAL) / COUNT(*) FROM superhero