Create test table:
`CREATE TABLE test (`id` Int32) ENGINE = MySQL('localhost:3306', '', 'test', 'user', 'pass')`

Attempt insert:
`INSERT INTO test VALUES(1)`

CH sending SQL:
`INSERT INTO ``.`test` (`id`) VALUES (1)`

"``." - sending empty database name in generated SQL

However SELECT statement working with empty database name correctrly

P.S.
This can be useful when working with databases such as sphinx
for (size_t id = left; id <= right; ++id)
                {
                    String id_str = toString<UInt64>(id);
                    if (add_leading_zeroes)
                    {
                        while (id_str.size() < len)
                            id_str = "0" + id_str;
                    }
                    buffer.push_back(id_str);
                }
            }
            else if (have_splitter) 
                buffer = parseRemoteDescription(description, i + 1, m, separator, max_addresses);
            else                     
                buffer.push_back(description.substr(i, m - i + 1));
            
            append(cur, buffer, max_addresses);
            i = m;
        }
        else if (description[i] == separator)
        {
            
            res.insert(res.end(), cur.begin(), cur.end());
            cur.clear();
        }
        else
        {
            
            std::vector<String> buffer;
            buffer.push_back(description.substr(i, 1));