在BigQuery中，Simba JDBC驱动程序不支持在事务中使用DDL语句。如果您想在事务中执行DDL语句，可以使用BigQuery的原生Java客户端库进行操作。

下面是一个使用原生Java客户端库在事务中执行DDL语句的示例代码：

import com.google.cloud.bigquery.BigQuery;
import com.google.cloud.bigquery.BigQueryOptions;
import com.google.cloud.bigquery.Job;
import com.google.cloud.bigquery.JobInfo;
import com.google.cloud.bigquery.QueryJobConfiguration;
import com.google.cloud.bigquery.QueryJobConfiguration.Builder;
import com.google.cloud.bigquery.TableId;
import com.google.cloud.bigquery.Transaction;
import com.google.cloud.bigquery.TransactionManager;
import com.google.cloud.bigquery.TransactionManager.TransactionState;
import com.google.cloud.bigquery.TransactionManagerImpl;

public class BigQueryDDLTransactionExample {

    public static void main(String[] args) {
        BigQuery bigquery = BigQueryOptions.getDefaultInstance().getService();
        TransactionManager transactionManager = bigquery.transactionManager();
        Transaction transaction = transactionManager.begin();

        try {
            // 在事务中执行DDL语句
            String ddlStatement = "CREATE TABLE mydataset.mytable (col1 INT64, col2 STRING)";
            QueryJobConfiguration queryConfig = QueryJobConfiguration.newBuilder(ddlStatement).build();
            
            Builder builder = QueryJobConfiguration.newBuilder(ddlStatement);
            builder.setUseLegacySql(false);
            QueryJobConfiguration queryConfig = builder.build();
            
            Job job = transaction.create(JobInfo.newBuilder(queryConfig).setDryRun(true).build());
            job = job.waitFor();
            
            // 检查DDL语句是否有效
            if (job.getStatus().getError() != null) {
                throw new RuntimeException("DDL statement is invalid: " + job.getStatus().getError());
            }
            
            // 提交事务
            transaction.commit();
            System.out.println("DDL statement executed successfully in a transaction");
        } catch (Exception e) {
            // 回滚事务
            transaction.rollback();
            System.out.println("DDL statement execution failed in a transaction: " + e.getMessage());
        }
    }
}

这个示例代码演示了如何创建一个新的表（使用DDL语句）并将其包含在一个事务中。请注意，此示例使用了BigQuery的原生Java客户端库，而不是Simba JDBC驱动程序。