java - Cassandra Java 请求

Question

我尝试使用 Cassandra 数据库在 Java 中执行一个简单的请求，但我不明白我的示例它不起作用:

public class Test {

    public static void main( String[] args )
    {
        Cluster cluster = Cluster.builder()
                          .addContactPoints("127.0.0.1")
                          .build();
        Session session = cluster.connect("test");

        ResultSet results = session.execute("SELECT * FROM datatest");
        for ( Row row : results ) {
            System.out.println(row.getString("name"));
        }
    }

}

当我执行我的代码时出现这个错误:

[main] INFO com.datastax.driver.core.policies.DCAwareRoundRobinPolicy - Using data-center name 'datacenter1' for DCAwareRoundRobinPolicy (if this is incorrect, please provide the correct datacenter name with DCAwareRoundRobinPolicy constructor)
[main] INFO com.datastax.driver.core.Cluster - New Cassandra host /127.0.0.1:9042 added
Exception in thread "main" java.lang.IllegalArgumentException: name is not a column defined in this metadata
    at com.datastax.driver.core.ColumnDefinitions.getAllIdx(ColumnDefinitions.java:273)
    at com.datastax.driver.core.ColumnDefinitions.getFirstIdx(ColumnDefinitions.java:279)
    at com.datastax.driver.core.ArrayBackedRow.getIndexOf(ArrayBackedRow.java:69)
    at com.datastax.driver.core.AbstractGettableData.getString(AbstractGettableData.java:137)
    at fakemillions.Test.main(Test.java:23)

这是我的数据库:

My database screenshot

Answer 1

听起来您还没有在表 datatest 中定义名称为“name”的列。我以前没有使用过 Datastax 驱动程序，但作为 documentation说 IllegalArgumentException 被抛出如果

name is not part of the ResultSet this row is part of, i.e. if !this.columns().names().contains(name)

最好提供datatest表的创建方式。