sql - Android Room Embedded Relation 忽略 SQL where 条件

Question

我是一个 SQL 菜鸟，不明白为什么我的语句的行为方式如此。它在 Android Room DAO 中使用并返回不需要的结果。

我在两个表中有这个示例数据:


我有这样的声明:

@Transaction
    @Query("Select Distinct Category.* " +
            "from Category " +
            "inner join Items on Category.ID = Items.Category " +
            "where IsExcluded = 0 " + 
            "order by lower( Category.Name ) asc")
    LiveData<List<CatViewWithItemList>> getCatViewWithItemListGlobal();

结果由一个简单的 POJO 接收:

public class CatViewWithItemList  {

    @Embedded
    public Cat myCat;

    @Relation(parentColumn = "ID",
            entityColumn = "Category") public List<ItemS> ItemList;

问题:
我不明白结果:



为什么第 5 项被退回？它应该被 where 子句排除。我的陈述有错误吗？

MikeT 构建了一个包含相同错误的示例应用程序:


(编辑:我现在放弃了 bool 转换器，Room 似乎在没有它的情况下解析 bool 值)或者这可能是由于我的 bool 型简单类型转换器死了造成的吗？ 1 和 0 实际上是 bool 值的占位符:

@TypeConverter
    public Boolean fromInt(int value) {
        return value == 0 ? false : true;
    }

    @TypeConverter
    public int toInt(Boolean bValue) {
        if (bValue == false) {
            return 0;
        } else {
            return 1;
        }
    }

感谢您的阅读!

编辑:
非常感谢@Angela。她 test表明 sql 语句很好，并且该行为是由 sqlite 的特性或接收器 pojo 中的嵌入关系引起的。有人对此有什么建议吗？

编辑:
MikeT 解释了为什么我想做的事情在房间关系上似乎是不可能的——至少只要没有人证明不同。在他的回答中，他提供了另一种选择。

Answer 1

我相信这要么是由于您的死简单转换器，要么可能是由于项目实体的定义方式(我使用了 bool 值 用于 排除了 并且它似乎在没有转换器的情况下工作正常)。

那是使用我的 Items Entity 版本:-

@Entity(foreignKeys = @ForeignKey(entity = Category.class,parentColumns = "id", childColumns = "category", onDelete =  CASCADE))
public class Items {
    @PrimaryKey(autoGenerate = true)
    private long id;
    private String category;
    private boolean isexcluded;


    public void setCategory(String category) {
        this.category = category;
    }

    public void setId(long id) {
        this.id = id;
    }

    public void setIsexcluded(boolean isexcluded) {
        this.isexcluded = isexcluded;
    }

    public String getCategory() {
        return this.category;
    }

    public long getId() {
        return this.id;
    }

    public boolean isIsexcluded() {
        return this.isexcluded;
    }
}

以及以下类别的 DAO:-

@Dao
interface CategoryDAO {
    @Query("SELECT * FROM Category")
    List<Category> getAllcategories();

    @Query("SELECT DISTINCT Category.* " +
            "FROM CATEGORY " +
            "INNER JOIN ITEMS ON category.id = Items.category " +
            "WHERE isexcluded = 0 " +
            "ORDER BY lower(category.name)")
    List<Category> getSpeacial();

    @Query("SELECT DISTINCT Category.* " +
            "FROM CATEGORY " +
            "INNER JOIN ITEMS ON category.id = Items.category " +
            "WHERE isexcluded = 0 " +
            "ORDER BY lower(category.name)")
    List<CatViewWithItemList> getSpeacial2();

    @Insert
    public long[] insertCategory(Category... Category);
}

随着

new Thread(new Runnable() {
            @Override
            public void run() {
                //mRoomDB.categoryDao().insertCategory(initialCategories());
                //mRoomDB.itemsDAO().insertItem(initialItems());
                List<Category> categoryList = mRoomDB.categoryDao().getAllcategories();
                List<Items> itemsList = mRoomDB.itemsDAO().getAllItems();
                for (Category c: categoryList) {
                    Log.d("CATEGORY","Category is " + c.getName() + " refrence is " + c.getId());
                }
                for (Items i: itemsList) {
                    Log.d("ITEM","Item is " + i.getId() + " Category reference is " + i.getCategory() + " Is Excluded is " + Boolean.toString(i.isIsexcluded()));
                }
                List<Category> categoryList2 = mRoomDB.categoryDao().getSpeacial();
                for (Category c: categoryList2) {
                    Log.d("CATEGORY2","Category is " + c.getName() + " reference is " + c.getId());
                }
                List<CatViewWithItemList> catViewWithItemLists = mRoomDB.categoryDao().getSpeacial2();
                for (CatViewWithItemList cvwil: catViewWithItemLists) {
                    Log.d("CATVIEWITEM","Category = " + cvwil.myCat.getId() + " ID = " + cvwil.ItemList.get(0).getId() + " IsExcluded = " + Boolean.toString(cvwil.ItemList.get(0).isIsexcluded()));
                }
            }
        }).start();

与 :-

public class CatViewWithItemList {

    @Embedded
    public Category myCat;

    @Relation(parentColumn = "id",
            entityColumn = "category")
    public List<Items> ItemList;
}

然后结果是(第一部分基础数据(哦，所以我不能拼第三个:))):-

2018-12-19 21:47:05.376 2109-2125/? D/CATEGORY: Category is firstname refrence is a
2018-12-19 21:47:05.377 2109-2125/? D/CATEGORY: Category is secondname refrence is b
2018-12-19 21:47:05.377 2109-2125/? D/CATEGORY: Category is thridname refrence is c
2018-12-19 21:47:05.377 2109-2125/? D/ITEM: Item is 1 Category reference is a Is Excluded is false
2018-12-19 21:47:05.377 2109-2125/? D/ITEM: Item is 2 Category reference is c Is Excluded is false
2018-12-19 21:47:05.377 2109-2125/? D/ITEM: Item is 3 Category reference is null Is Excluded is false
2018-12-19 21:47:05.377 2109-2125/? D/ITEM: Item is 4 Category reference is b Is Excluded is false
2018-12-19 21:47:05.377 2109-2125/? D/ITEM: Item is 5 Category reference is b Is Excluded is true
2018-12-19 21:47:05.378 2109-2125/? D/ITEM: Item is 6 Category reference is null Is Excluded is true

然后是两组结果:-

2018-12-19 21:47:05.379 2109-2125/? D/CATEGORY2: Category is firstname reference is a
2018-12-19 21:47:05.380 2109-2125/? D/CATEGORY2: Category is secondname reference is b
2018-12-19 21:47:05.380 2109-2125/? D/CATEGORY2: Category is thridname reference is c


2018-12-19 21:47:05.382 2109-2125/? D/CATVIEWITEM: Category = a ID = 1 IsExcluded = false
2018-12-19 21:47:05.382 2109-2125/? D/CATVIEWITEM: Category = b ID = 4 IsExcluded = false
2018-12-19 21:47:05.382 2109-2125/? D/CATVIEWITEM: Category = c ID = 2 IsExcluded = false

额外的

我相信您的问题不在于查询，而在于 CatViewItemList 因为您正在使用与该类别相关的所有项目填充项目列表，而与查询无关/之后(我认为，将项目列表嵌入到类别中)。这确实让我感到困惑，因为你真的只想要特定的相关项目(我刚刚在我的代码中捕获了第一个)，例如 cvwil.ItemList.get(0).isIsexcluded()幸运的是 4 出现在 5 之前，所以 isexcluded 显示为假。

我相信您也许应该从项目中解决这个问题，加入类别，例如就像是

SELECT * 
FROM Items 
JOIN Category ON Items.category = category.id
WHERE Items.isexcluded = 0 
ORDER BY category.name ASC;

我将更新 gitHub 上的代码为此(请注意，我已将 Category 表更改为具有 categoryid 而不是 id 的唯一列名。)

结果现在是(注意添加了另一个类别和另外 2 个项目颠倒顺序，即第一个项目(id 7)被排除为真，然后 id 8 为假):-

2018-12-20 21:39:56.971 9136-9160/so53839431.so53839431roomrelationship D/CATEGORY: Category is firstname Category ID is a
2018-12-20 21:39:56.971 9136-9160/so53839431.so53839431roomrelationship D/CATEGORY: Category is secondname Category ID is b
2018-12-20 21:39:56.971 9136-9160/so53839431.so53839431roomrelationship D/CATEGORY: Category is thirdname Category ID is c
2018-12-20 21:39:56.971 9136-9160/so53839431.so53839431roomrelationship D/CATEGORY: Category is fourthname Category ID is d
2018-12-20 21:39:56.971 9136-9160/so53839431.so53839431roomrelationship D/ITEM: Item is 1 Category reference is a Is Excluded is false
2018-12-20 21:39:56.971 9136-9160/so53839431.so53839431roomrelationship D/ITEM: Item is 2 Category reference is c Is Excluded is false
2018-12-20 21:39:56.971 9136-9160/so53839431.so53839431roomrelationship D/ITEM: Item is 3 Category reference is null Is Excluded is false
2018-12-20 21:39:56.971 9136-9160/so53839431.so53839431roomrelationship D/ITEM: Item is 4 Category reference is b Is Excluded is false
2018-12-20 21:39:56.971 9136-9160/so53839431.so53839431roomrelationship D/ITEM: Item is 5 Category reference is b Is Excluded is true
2018-12-20 21:39:56.971 9136-9160/so53839431.so53839431roomrelationship D/ITEM: Item is 6 Category reference is null Is Excluded is true
2018-12-20 21:39:56.971 9136-9160/so53839431.so53839431roomrelationship D/ITEM: Item is 7 Category reference is d Is Excluded is true
2018-12-20 21:39:56.971 9136-9160/so53839431.so53839431roomrelationship D/ITEM: Item is 8 Category reference is d Is Excluded is false
2018-12-20 21:39:56.972 9136-9160/so53839431.so53839431roomrelationship D/ITEMWITHCAT: Item id =1 Category reference is a Is Excluded is false Referenced Category is a Referenced Category name is firstname
2018-12-20 21:39:56.972 9136-9160/so53839431.so53839431roomrelationship D/ITEMWITHCAT: Item id =2 Category reference is c Is Excluded is false Referenced Category is c Referenced Category name is thirdname
2018-12-20 21:39:56.972 9136-9160/so53839431.so53839431roomrelationship D/ITEMWITHCAT: Item id =4 Category reference is b Is Excluded is false Referenced Category is b Referenced Category name is secondname
2018-12-20 21:39:56.972 9136-9160/so53839431.so53839431roomrelationship D/ITEMWITHCAT: Item id =8 Category reference is d Is Excluded is false Referenced Category is d Referenced Category name is fourthname