pgsql查看字段数据类型函数？

SELECT pg_proc.proname AS "函数名称", pg_type.typname AS "返回值数据类型", pg_proc.pronargs AS "参数个数" FROM pg_proc JOIN pg_type ON (pg_proc.prorettype = pg_type.oid) WHERE pg_type.typname != 'void' AND pronamespace = (SELECT pg_namespace.oid FROM pg_namespace WHERE nspname = 'public');