Rename pascal case tables to snake case in postgresql

rename_pascal_tablenames.sql

SELECT ddlsql || regexp_replace(name, E'^_',E'','g') As ddlsql FROM  (SELECT 'ALTER TABLE ' || quote_ident(t.table_schema) || '.'
  || quote_ident(t.table_name) || ' RENAME TO '  As ddlsql, quote_ident(lower(regexp_replace(t.table_name, E'([A-Z])', E'\_\\1','g'))) || ';' as name
  FROM information_schema.tables As t
  WHERE t.table_schema NOT IN('information_schema', 'pg_catalog') 
      AND t.table_name <> lower(t.table_name) 
  ORDER BY t.table_schema, t.table_name) x;

Thank you very much.

Rename "camelCaseColumnNames":

SELECT
  'ALTER TABLE '
  || quote_ident(c.table_schema)
  || '.'
  || quote_ident(c.table_name)
  || ' RENAME COLUMN '
  || quote_ident(c.column_name)
  || ' TO '
  || quote_ident(
       lower(
         regexp_replace(
           regexp_replace(c.column_name, '([A-Z])', '_\1', 'g')
         , '^_', '', 'g')
       )
     )
  || ';'
FROM information_schema.columns AS c
WHERE c.table_schema NOT IN('information_schema','pg_catalog')
  AND c.column_name <> lower(c.column_name)
ORDER BY c.table_schema, c.table_name, c.ordinal_position;

ChatGPT and other LLMs can help in generating similar queries for other cases, including enum types, different cases, etc.