Again, there is a misunderstanding. "null" is not the same as null. One is an opaque string, the other is a language value. One should NEVER build systems that

Again, there is a misunderstanding. "null" is not the same as null. One is an opaque string, the other is a language value. One should NEVER build systems that confuse the two, or allow one to be interpreted as the other. If you export data, export nulls as nulls, not "nulls". If you import data, NEVER interpret what's inside strings.