def convert_obj_to_schema(obj:dict) -> str:
    schema = f"CREATE DATABASE {obj['db_id']}; USE {obj['db_id']};"
    
    tables = {}
    for table_name in obj['table_names']:
        table_name = "_".join(table_name.split(" "))
        tables[table_name] = []

    for col_idx, column in enumerate(obj['column_names']):
        table_id, column_name = column
        # _ combination
        column_name = "_".join(column_name.split(" "))

        if table_id == -1:
            continue
        table_name = obj['table_names'][table_id]
        column_type = obj['column_types'][col_idx]

        # _ combination
        table_name = "_".join(table_name.split(" "))

        column_attributes = [column_name, column_type]
        if col_idx in obj['primary_keys']:
            column_attributes.append("PRIMARY KEY")
        
        tables[table_name].append(column_attributes)

        for fk in obj['foreign_keys']:
            if col_idx == fk[1]:
                table_id_other, column_name_other = obj['column_names'][fk[0]]
                table_name_other = obj['table_names'][table_id_other]

                column_name_other = "_".join(column_name_other.split(" "))
                table_name_other = "_".join(table_name_other.split(" "))
                tables[table_name].append([f"FOREIGN KEY {column_name} REFERENCES {table_name_other}({column_name_other})"])
        
    for table_name in tables:
        
        column_attributes = ""
        for idx, column_attribute in enumerate(tables[table_name]):
            column_attributes += " ".join(column_attribute) + ","
        column_attributes = column_attributes[:-1] # remove endless ','

        schema += f" CREATE TABLE {table_name}({column_attributes});"
    
    return {
        "db_id": obj['db_id'],
        "schema": schema
    }