generate_add_foreign_keys_ddl_to_target_table.sql

-- Generate DDL to add back foreign keys
SELECT
    'ALTER TABLE ' || nsp.nspname || '.' || cls.relname || ' ADD CONSTRAINT ' || conname || ' FOREIGN KEY (' || STRING_AGG(att.attname, ', ') OVER (PARTITION BY conname) || ')' || ' REFERENCES ' || refnsp.nspname || '.' || refcls.relname || ' (' || STRING_AGG(refatt.attname, ', ') OVER (PARTITION BY conname) || ')' || CASE WHEN confupdtype = 'c' THEN
        ' ON UPDATE CASCADE'
    WHEN confupdtype = 'n' THEN
        ' ON UPDATE SET NULL'
    WHEN confupdtype = 'd' THEN
        ' ON UPDATE SET DEFAULT'
    ELSE
        ''
    END || CASE WHEN confdeltype = 'c' THEN
        ' ON DELETE CASCADE'
    WHEN confdeltype = 'n' THEN
        ' ON DELETE SET NULL'
    WHEN confdeltype = 'd' THEN
        ' ON DELETE SET DEFAULT'
    ELSE
        ''
    END || ';'
FROM
    pg_constraint con
    JOIN pg_class cls ON con.conrelid = cls.oid
    JOIN pg_namespace nsp ON cls.relnamespace = nsp.oid
    JOIN pg_class refcls ON con.confrelid = refcls.oid
    JOIN pg_namespace refnsp ON refcls.relnamespace = refnsp.oid
    JOIN pg_attribute att ON att.attnum = ANY (con.conkey)
        AND att.attrelid = con.conrelid
    JOIN pg_attribute refatt ON refatt.attnum = ANY (con.confkey)
        AND refatt.attrelid = con.confrelid
WHERE
    refcls.relname = 'users' -- replace with your table name
    AND refnsp.nspname = 'rideshare' -- replace with your schema if different
GROUP BY
    conname,
    nsp.nspname,
    cls.relname,
    refnsp.nspname,
    refcls.relname,
    confupdtype,
    confdeltype,
    att.attname,
    refatt.attname;