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
{
    String res(x.size(), '\0');
    {
        WriteBufferFromString wb(res);
        writeBackQuotedStringMySQL(x, wb);
    }
    return res;
}
StorageMySQL::StorageMySQL(