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
{
    std::vector<String> res;
    std::vector<String> cur;
    
    if (l >= r)
    {
        res.push_back("");
        return res;
    }
    for (size_t i = l; i < r; ++i)
    {
        
        if (description[i] == '{')
        {
            int cnt = 1;
            int last_dot = -1; 
            size_t m;
            std::vector<String> buffer;
            bool have_splitter = false;
            
            for (m = i + 1; m < r; ++m)
            {
                if (description[m] == '{') ++cnt;
                if (description[m] == '}') --cnt;
                if (description[m] == '.' && description[m-1] == '.') last_dot = m;
                if (description[m] == separator) have_splitter = true;
                if (cnt == 0) break;
            }
            if (cnt != 0)