Enumerated types with zero or one value

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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.
Type Problem detection (Each row in the result could represent a flaw in the design)
Reliability High (Few or no false-positive results)
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 
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 that help generate fixes for the identified problem.

SQL Query to Generate FixDescription
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

This query belongs to the following collections:

NameDescription
Find problems automaticallyQueries, 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

This query is classified under the following categories:

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