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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{
    if (rename_query.exchange)
        throw Exception("Cannot execute exchange for external ddl query.", ErrorCodes::NOT_IMPLEMENTED);
}
ASTs InterpreterRenameImpl::getRewrittenQueries(
    const InterpreterRenameImpl::TQuery & rename_query, const Context & context, const String & mapped_to_database, const String & mysql_database)
{
    ASTRenameQuery::Elements elements;
    for (const auto & rename_element : rename_query.elements)
    {
        const auto & to_database =  resolveDatabase(rename_element.to.database, mysql_database, mapped_to_database, context);
        const auto & from_database =  resolveDatabase(rename_element.from.database, mysql_database, mapped_to_database, context);
        if ((from_database == mapped_to_database || to_database == mapped_to_database) && to_database != from_database)
            throw Exception("Cannot rename with other database for external ddl query.", ErrorCodes::NOT_IMPLEMENTED);
        if (from_database == mapped_to_database)
        {
            elements.push_back(ASTRenameQuery::Element());
            elements.back().from.database = mapped_to_database;
            elements.back().from.table = rename_element.from.table;
            elements.back().to.database = mapped_to_database;
            elements.back().to.table = rename_element.to.table;
        }
    }
    if (elements.empty())
        return ASTs{};
    auto rewritten_query = std::make_shared<ASTRenameQuery>();
    rewritten_query->elements = elements;
    return ASTs{rewritten_query};
}
void InterpreterAlterImpl::validate(const InterpreterAlterImpl::TQuery & , const Context & )