```
Caught exception while loading metadata: Code: 501, e.displayText() = DB::Exception: Cannot create MySQL database, because Code: 393, e.displayText() 
= DB::Exception: There is no query, Stack trace (when copying this message, always include the lines below):

0. /home/milovidov/ClickHouse/build_gcc9/../contrib/poco/Foundation/src/Exception.cpp:27: Poco::Exception::Exception(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, 
int) @ 0x1074687c in /usr/bin/clickhouse
1. /home/milovidov/ClickHouse/build_gcc9/../src/Common/Exception.cpp:37: DB::Exception::Exception(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, int) @ 0x7867c29 in
 /usr/bin/clickhouse
2. /home/milovidov/ClickHouse/build_gcc9/../contrib/libcxx/include/string:2134: DB::Context::getQueryContext() const (.cold) @ 0xd202416 in /usr/bin/clickhouse
3. /home/milovidov/ClickHouse/build_gcc9/../src/Interpreters/Context.h:457: DB::DatabaseConnectionMySQL::DatabaseConnectionMySQL(DB::Context const&, std::__1::basic_string<char, std::__1::char_traits<char>, std:
:__1::allocator<char> > const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, DB::ASTStorage const*, std::__1::basic_string<char, std::__1::char_traits<char>, std:
:__1::allocator<char> > const&, mysqlxx::Pool&&) @ 0xd408d7c in /usr/bin/clickhouse
```

```
ATTACH DATABASE conv_main
ENGINE = MySQL('hostname:3306', 'db', 'metrika', 'password')
```
{
    std::lock_guard<std::mutex> lock{mutex};
    if (!local_tables_cache.count(table_name))
        throw Exception("Cannot attach table " + backQuoteIfNeed(database_name) + "." + backQuoteIfNeed(table_name) +
            " because it does not exist.", ErrorCodes::UNKNOWN_TABLE);
    if (!remove_or_detach_tables.count(table_name))
        throw Exception("Cannot attach table " + backQuoteIfNeed(database_name) + "." + backQuoteIfNeed(table_name) +
            " because it already exists.", ErrorCodes::TABLE_ALREADY_EXISTS);
    
    
    local_tables_cache[table_name].second = storage;
    remove_or_detach_tables.erase(table_name);
    Poco::File remove_flag(getMetadataPath() + '/' + escapeForFileName(table_name) + suffix);
    if (remove_flag.exists())
        remove_flag.remove();
}
StoragePtr DatabaseConnectionMySQL::detachTable(const String & table_name)