i use
my steps
1. create a new database ckdb on mysql, then  create table t1(a int, primary key(a)); and insert some rows
2. SET allow_experimental_database_materialize_mysql=1; at clickhouse, 
3. CREATE DATABASE ckdb ENGINE = MaterializeMySQL('127.0.0.1:3306', 'ckdb', 'root', 'A123b_456');
4. use ckdb and select * from t1 ok
5. create table dzm as select * from others in mysql ----> cannot see dzm in clickhouse, but if select * from t1, reports
```
Code: 48. DB::Exception: Received from localhost:9000. DB::Exception: The ckdb.dzm cannot be materialized, because there is no primary keys..
```
6. create table t2(a int,b int primary a);----> cannot see t2 in clickhouse, , but if select * from t1, reports
```
Code: 44. DB::Exception: Received from localhost:9000. DB::Exception: Sorting key cannot contain nullable columns.
```
<del>7. if i drop ckdb and recreate it, all tables can be selected </del>
7.if there are some 'bad' tables in a database, all tables in that database cannot be selected

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rewritten_command->rename_to = std::make_shared<ASTIdentifier>(alter_command->column_name);
                rewritten_alter_query->command_list->add(rewritten_command);
            }
        }
        else if (alter_command->type == MySQLParser::ASTAlterCommand::MODIFY_COLUMN)
        {
            String new_column_name;
            {
                auto rewritten_command = std::make_shared<ASTAlterCommand>();
                rewritten_command->type = ASTAlterCommand::MODIFY_COLUMN;
                rewritten_command->first = alter_command->first;
                auto modify_columns = getColumnsList(alter_command->additional_columns);
                if (modify_columns.size() != 1)
                    throw Exception("It is a bug", ErrorCodes::LOGICAL_ERROR);
                new_column_name = modify_columns.front().name;
                if (!alter_command->old_name.empty())
                    modify_columns.front().name = alter_command->old_name;
                rewritten_command->col_decl = InterpreterCreateQuery::formatColumns(modify_columns)->children[0];
                if (!alter_command->column_name.empty())
                {
                    rewritten_command->column = std::make_shared<ASTIdentifier>(alter_command->column_name);
                    rewritten_command->children.push_back(rewritten_command->column);
                }
                rewritten_alter_query->command_list->add(rewritten_command);
            }
            if (!alter_command->old_name.empty() && alter_command->old_name != new_column_name)
            {
                auto rewritten_command = std::make_shared<ASTAlterCommand>();
                rewritten_command->type = ASTAlterCommand::RENAME_COLUMN;
                rewritten_command->column = std::make_shared<ASTIdentifier>(alter_command->old_name);