Rename PascalCase tables and columns to snake_case in PostgreSQL

pascal_to_camel.sql

-- Rename tables
DO $$
DECLARE
    table_record RECORD;
BEGIN
    -- Loop through each table
    FOR table_record IN (SELECT table_name FROM information_schema.tables WHERE table_schema = 'public' AND table_type = 'BASE TABLE') LOOP
        EXECUTE FORMAT('ALTER TABLE public.%I RENAME TO %I', table_record.table_name, lower(regexp_replace(table_record.table_name, '(.)([A-Z])', '\1_\2', 'g')));
    END LOOP;
END $$;

-- Rename columns
DO $$
DECLARE
    table_record RECORD;
    column_record RECORD;
BEGIN
    -- Loop through each table
    FOR table_record IN (SELECT table_name FROM information_schema.tables WHERE table_schema = 'public' AND table_type = 'BASE TABLE') LOOP
        -- Loop through each column in the table
        FOR column_record IN (SELECT column_name FROM information_schema.columns WHERE table_schema = 'public' AND table_name = table_record.table_name) LOOP
            EXECUTE FORMAT('ALTER TABLE public.%I RENAME COLUMN %I TO %I', table_record.table_name, column_record.column_name, lower(regexp_replace(column_record.column_name, '(.)([A-Z])', '\1_\2', 'g')));
        END LOOP;
    END LOOP;
END $$;