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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#include <Parsers/MySQL/ASTDeclareColumn.h>
#include <Parsers/ASTIdentifier.h>
#include <Parsers/ParserDataType.h>
#include <Parsers/ExpressionListParsers.h>
#include <Parsers/ExpressionElementParsers.h>
#include <Parsers/MySQL/ASTDeclareOption.h>
#include <Parsers/MySQL/ASTDeclareReference.h>
#include <Parsers/MySQL/ASTDeclareConstraint.h>
namespace DB
{
namespace MySQLParser
{
ASTPtr ASTDeclareColumn::clone() const
{
    auto res = std::make_shared<ASTDeclareColumn>(*this);
    res->children.clear();
    if (data_type)
    {
        res->data_type = data_type->clone();
        res->children.emplace_back(res->data_type);
    }
    if (column_options)
    {
        res->column_options = column_options->clone();
        res->children.emplace_back(res->column_options);
    }
    return res;
}
static inline bool parseColumnDeclareOptions(IParser::Pos & pos, ASTPtr & node, Expected & expected)