Using conditionals to determine the returned value

Query goal:

Use SQL language instead of PL/pgSQL where possible. Instead of using an IF statement, you can check as to whether the data modification succeeded or not by using the RETURNING clause in the data modification statement.

Notes about the query:

Refers to the column pg_proc.prokind and thus works starting from PostgreSQL 11. There could be multiple routines with the same name but with different parameters in the same schema (overloading). Thus, for the unique identification of the routine it is necessary to present also its parameters in addition to the schema name and routine name. In the returned body of routine the query replaces each newline character with the line break (br) tag for the better readability in case the query result is displayed in a web browser.

Query type:

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

Query reliability:

Medium (Medium number of false-positive results)

Query license:

MIT License

Fixing suggestion:

Instead of using conditionals to determine the returned value, one can check as to whether the data modification succeeded or not by using the RETURNING clause in the data modification statement. In this case it might be possible the routine written in PL/pgSQL with the routine written in SQL.

Data source:

INFORMATION_SCHEMA+system catalog

SQL query:

Click on query to copy it

SELECT 
  pg_namespace.nspname AS function_schema, 
  pg_proc.proname AS function_name, 
  pg_get_function_identity_arguments(pg_proc.oid) AS parameters,
  regexp_replace(pg_get_functiondef(pg_proc.oid),'[\r\n]','<br>','g')  AS function_src
FROM 
  pg_catalog.pg_proc, 
  pg_catalog.pg_namespace,
  pg_catalog.pg_language
WHERE 
  pg_proc.pronamespace = pg_namespace.oid 
  AND pg_proc.prolang = pg_language.oid 
  AND pg_language.lanname='plpgsql' 
  AND pg_proc.prokind='f' 
  AND pg_proc.proname NOT IN ('f_assume_you_must_use_files', 'f_check_format_comma_separated_list', 'f_check_password', 'f_default_value_with_no_match') 
  AND pg_get_functiondef(pg_proc.oid)~*'(INSERT|UPDATE|DELETE)[^;]+;[[:space:]]+IF([[:space:]]+|[[:space:]]+NOT[[:space:]]+)FOUND[[:space:]]+THEN[[:space:]]*RETURN[[:space:]]+(TRUE|FALSE)[[:space:]]*;[[:space:]]*ELSE[[:space:]]*RETURN[[:space:]]+(TRUE|FALSE)[[:space:]]*;[[:space:]]*END[[:space:]]+IF'
 AND pg_namespace.nspname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL)
ORDER BY function_schema, function_name, parameters;

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
Does not work in some earlier PostgreSQL version	Queries of this category provide information that was not available in some earlier PostgreSQL version
User-defined routines	Queries of this category provide information about the user-defined routines

Category name

Category description

Does not work in some earlier PostgreSQL version

Queries of this category provide information that was not available in some earlier PostgreSQL version

User-defined routines

Queries of this category provide information about the user-defined routines

Reference materials for further reading

Reference
https://www.postgresql.org/docs/current/dml-returning.html

Reference

https://www.postgresql.org/docs/current/dml-returning.html