Question

我正在编写一个数据库，用于保存Android应用程序中有关单词的信息。我建立了两个实体：Group和VocaNote。在Group和VocaNote之间，我使用一对多关系将VocaNote数组保存在不同的组中。

小组课程

@Entity(indices = {
    @Index(value = {"language", "nameGroup"}, unique = true)
}
)
public class Group {

@PrimaryKey(autoGenerate = true)
public long id;

@ColumnInfo(name = "language")
public String language;

@ColumnInfo(name = "name_group")
public String nameGroup;
}

VocaNote类

    @Entity(foreignKeys = @ForeignKey(entity = Group.class,
    parentColumns = "id",
    childColumns = "group_id",
    onDelete = CASCADE))
  public class VocaNote {

@PrimaryKey(autoGenerate = true)
public long id;

@ColumnInfo(name = "origin_word")
public String originWord;

@ColumnInfo(name = "translation")
public String translation;

@ColumnInfo(name = "studied_word")
public int studied;

@ColumnInfo(name = "group_id")
public int groupId;

}

之后，我为上述实体类添加了单独的DAO

VocaNoteDao

@Dao
public interface VocaNoteDao {

@Query("SELECT * FROM vocanote")
List<VocaNote> getAllVocaNote();

@Query("SELECT * FROM vocanote WHERE id = :id")
VocaNote getByIdVocaNote(long id);

@Insert
void insert(VocaNote vocaNote);

@Update
void update(VocaNote vocaNote);

@Delete
void delete (VocaNote vocaNote);
}

GroupDao

@Dao
public interface GroupDao {
@Insert
void insert(Group group);

@Update
void update(Group group);

@Delete
void delete (Group group);

@Query("SELECT * FROM group")
List<Group> getAllGroup();

@Query("SELECT * FROM group WHERE id = :id")
Group getByIdGroup(long id);

}

这里我遇到了问题。当我尝试从组表进行查询时，而是收到编译错误表或子查询预期，得到组。请告诉我，我该怎么处理？我有组实体，但我的IDE不想看到/

Answer 1

使用方括号转义保留关键字

@Query("SELECT * FROM [group] WHERE id = :id")
Group getByIdGroup(long id);

Answer 2

您必须检查表名。必须填写表名。甚至不能输入空字符串。

＆＃34;表或子查询预期，得到＆＃34; Android会议室错误

2 个答案: