Enumerated types with zero or one value

Query goal:

Fidn enumerated types with zero or one value. Type is a named finite set of values. The empty set is a set. A set with one value is a set. Thus, types with zero or one value are legal. In practical terms each type, usually, should contain at least two values.

Query type:

Problem detection (Each row in the result could represent a flaw in the design)

Query reliability:

High (Few or no false-positive results)

Query license:

MIT License

Fixing suggestion:

Add values to the type by using an ALTER TYPE statement or drop the type.

Data source:

INFORMATION_SCHEMA+system catalog

SQL query:

Click on query to copy it

SELECT nspname AS type_schema, typname, Count(enumtypid) AS number_of_labels
FROM pg_catalog.pg_type t LEFT JOIN pg_catalog.pg_enum e ON t.oid=e.enumtypid
INNER JOIN pg_catalog.pg_namespace n ON n.oid=t.typnamespace
WHERE nspname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL) AND 
t.typtype='e'
GROUP BY nspname, typname
HAVING Count(enumtypid)<=1
ORDER BY Count(enumtypid), nspname, typname;

SQL statements for generating SQL statements that help us to fix the problem

SQL query	Description
WITH suspected_types AS (SELECT nspname AS type_schema, typname FROM pg_catalog.pg_type t LEFT JOIN pg_catalog.pg_enum e ON t.oid=e.enumtypid INNER JOIN pg_catalog.pg_namespace n ON n.oid=t.typnamespace WHERE nspname NOT IN (SELECT schema_name FROM INFORMATION_SCHEMA.schemata WHERE schema_name<>'public' AND schema_owner='postgres' AND schema_name IS NOT NULL) AND t.typtype='e' GROUP BY nspname, typname HAVING Count(enumtypid)<=1) SELECT format('DROP TYPE %1$I.%2$I;', type_schema, typname) AS statements FROM suspected_types ORDER BY type_schema, typname;	Drop the type.

SQL query

Description

WITH suspected_types AS (SELECT nspname AS type_schema, typname
FROM pg_catalog.pg_type t LEFT JOIN pg_catalog.pg_enum e ON t.oid=e.enumtypid
INNER JOIN pg_catalog.pg_namespace n ON n.oid=t.typnamespace
WHERE nspname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL) AND 
t.typtype='e'
GROUP BY nspname, typname
HAVING Count(enumtypid)<=1)
SELECT format('DROP TYPE %1$I.%2$I;', type_schema, typname) AS statements
FROM suspected_types
ORDER BY type_schema, typname;

Drop the type.

Collections where the query belongs to

Collection name	Collection description
Find problems automatically	Queries, that results point to problems in the database. Each query in the collection produces an initial assessment. However, a human reviewer has the final say as to whether there is a problem or not .

Collection name

Collection description

Find problems automatically

Queries, that results point to problems in the database. Each query in the collection produces an initial assessment. However, a human reviewer has the final say as to whether there is a problem or not .

Categories where the query belongs to

Category name	Category description
Data types	Queries of this category provide information about the data types and their usage.
Stubs	Queries of this catergory provide information about stubs (piece of code used to stand in for some other programming functionality).
User-defined types	Queries of this category provide information about user-defined types in the database.

Category name

Category description

Data types

Queries of this category provide information about the data types and their usage.

Stubs

Queries of this catergory provide information about stubs (piece of code used to stand in for some other programming functionality).

User-defined types

Queries of this category provide information about user-defined types in the database.