Goal Find non-foreign key columns of base tables that probably (based on the column name) contain values that represent truth values but do not have NOT NULL constraint. Use two-valued logic (TRUE, FALSE) instead of three-valued logic (TRUE, FALSE, UNKNOWN). Because NULL in a Boolean column means unknown make all the columns mandatory.
Notes The query considers both column names in English and Estonian.
Type Problem detection Each row in the result could represent a flaw in the design
Reliability Medium Medium number of false-positive results
License MIT (opens in new tab)
Fixing Suggestion Make the column mandatory by declaring NOT NULL constraint to it.
Data Source INFORMATION_SCHEMA+system catalog
SQL Query 
WITH fk_columns AS (select target_schema as table_schema, target_table as table_name, a.attname as column_name
from (select 
(select nspname from pg_namespace where oid=c.relnamespace) as target_schema,
c.relname as target_table, 
c.oid as target_table_oid,
unnest(o.conkey) AS target_col
from pg_constraint o inner join pg_class c on c.oid = o.conrelid
where o.contype = 'f') t
inner join pg_attribute a on t.target_col = a.attnum and t.target_table_oid = a.attrelid and a.attisdropped = false)

SELECT c.table_schema, c.table_name, c.column_name, c.data_type, c.character_maximum_length, 
coalesce(c.column_default, d.domain_default) AS column_default
FROM INFORMATION_SCHEMA.columns AS c LEFT JOIN INFORMATION_SCHEMA.domains AS d USING (domain_schema, domain_name)
WHERE column_name~*'^(is|has|on)_' 
AND (c.data_type<>'boolean') 
AND c.is_nullable='YES'
AND (table_schema, table_name) IN (SELECT table_schema, table_name
FROM INFORMATION_SCHEMA.tables WHERE table_type='BASE TABLE') 
AND table_schema NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL)
AND NOT EXISTS (SELECT *
FROM fk_columns
WHERE fk_columns.table_schema=c.table_schema
AND fk_columns.table_name=c.table_name
AND fk_columns.column_name=c.column_name)
ORDER BY c.table_schema, c.table_name, c.column_name;

SQL statements that help generate fixes for the identified problem.

Fix Action #1
SELECT format('ALTER TABLE %1$I.%2$I ALTER COLUMN %3$I SET NOT NULL', A.table_schema, A.table_name , A.column_name) AS statements
FROM information_schema.columns A
INNER JOIN information_schema.tables T
ON A.table_schema = T.table_schema
AND A.table_name = T.table_name
INNER JOIN information_schema.schemata S
ON A.table_schema=S.schema_name
WHERE A.data_type<>'boolean' 
AND column_name~*'^(is|has|on)_' 
AND is_nullable='YES' 
AND T.table_type='BASE TABLE'
AND (A.table_schema = 'public'
OR S.schema_owner<>'postgres')
ORDER BY A.table_schema, A.table_name, A.column_name;

Apply the NOT NUL L constraint directly to the column.

SQL Query to Generate FixDescription
SELECT format('ALTER TABLE %1$I.%2$I ALTER COLUMN %3$I SET NOT NULL', A.table_schema, A.table_name , A.column_name) AS statements
FROM information_schema.columns A
INNER JOIN information_schema.tables T
ON A.table_schema = T.table_schema
AND A.table_name = T.table_name
INNER JOIN information_schema.schemata S
ON A.table_schema=S.schema_name
WHERE A.data_type<>'boolean' 
AND column_name~*'^(is|has|on)_' 
AND is_nullable='YES' 
AND T.table_type='BASE TABLE'
AND (A.table_schema = 'public'
OR S.schema_owner<>'postgres')
ORDER BY A.table_schema, A.table_name, A.column_name;
Apply the NOT NUL L constraint directly to the column.

Collections

This query belongs to the following collections:

Find problems about integrity constraints

A selection of queries that return information about the state of integrity constraints in the datadabase. Contains all the types of queries - problem detection, software measure, and general overview

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 .

NameDescription
Find problems about integrity constraintsA selection of queries that return information about the state of integrity constraints in the datadabase. Contains all the types of queries - problem detection, software measure, and general overview
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:

Boolean data

Queries of this category provide information about truth-values data that is kept in the database.

Comfortability of data management

Queries of this category provide information about the means that have been used to make the use or management of database more comfortable and thus, more efficient.

Data types

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

Missing data

Queries of this category provide information about missing data (NULLs) in a database.

Result quality depends on names

Queries of this category use names (for instance, column names) to try to guess the meaning of a database object. Thus, the goodness of names determines the number of false positive and false negative results.

NameDescription
Boolean dataQueries of this category provide information about truth-values data that is kept in the database.
Comfortability of data managementQueries of this category provide information about the means that have been used to make the use or management of database more comfortable and thus, more efficient.
Data typesQueries of this category provide information about the data types and their usage.
Missing dataQueries of this category provide information about missing data (NULLs) in a database.
Result quality depends on namesQueries of this category use names (for instance, column names) to try to guess the meaning of a database object. Thus, the goodness of names determines the number of false positive and false negative results.