Goal Find whether the database uses both CHAR(1) and VARCHAR(1) columns to register a single symbol.
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 (opens in new tab)
Data Source INFORMATION_SCHEMA only
SQL Query 
WITH short_chars AS (SELECT table_schema, table_name, column_name, ordinal_position, data_type
FROM INFORMATION_SCHEMA.columns
WHERE (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 data_type = 'character' AND 
character_maximum_length=1),
short_varchars AS (SELECT table_schema, table_name, column_name, ordinal_position, data_type
FROM INFORMATION_SCHEMA.columns
WHERE (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 data_type = 'character varying' AND 
character_maximum_length=1),
all_cols AS (SELECT table_schema, table_name, column_name, ordinal_position, data_type
FROM short_chars
UNION SELECT table_schema, table_name, column_name, ordinal_position, data_type
FROM short_varchars)
SELECT table_schema, table_name, column_name, data_type
FROM all_cols
WHERE EXISTS (SELECT * FROM short_chars) 
AND EXISTS (SELECT * FROM short_varchars)
ORDER BY data_type, table_schema, table_name, ordinal_position;

Fixing Suggestion

Use consistenly CHAR(1) in case of all the columns.

Collections

This query belongs to the following collections:

Find problems about base tables

A selection of queries that return information about the data types, field sizes, default values as well as general structure of base tables. 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 base tablesA selection of queries that return information about the data types, field sizes, default values as well as general structure of base tables. 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:

Data types

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

Inconsistencies

Queries of this catergory provide information about inconsistencies of solving the same problem in different places.

NameDescription
Data typesQueries of this category provide information about the data types and their usage.
InconsistenciesQueries of this catergory provide information about inconsistencies of solving the same problem in different places.