避免在sqlite中创建_id列

Question

我正在使用android.persistence.room来创建数据库。我有一个中间表，其中的行用其他两个表的PK标识，所以不需要id列（我没有使用游标）。我班里没有id字段，房间也没有抱怨。我添加了一个迁移，其中我创建了一个没有id列的新表;复制现有数据并重命名（sqlite中的典型drop column方法），仍然是id列。

@Entity(tableName = "recipe_ingredients",
        foreignKeys = {
            @ForeignKey(entity =
                    Recipe.class,
                    parentColumns = "id",
                    childColumns = "recipe",
                    onDelete = ForeignKey.CASCADE),
            @ForeignKey(entity =
                    Ingredient.class,
                    parentColumns = "id",
                    childColumns = "ingredient",
                    onDelete = ForeignKey.RESTRICT)
        },
        primaryKeys = {"recipe", "ingredient"})
public class RecipeIngredient {

//region members
    @ColumnInfo(name = "recipe")
private int mReceptId;
    @ColumnInfo(name = "ingredient")
private int mIngredientId;
    @Embedded
private Ingredient mIngredient;
    @ColumnInfo(name = "amount")
private double amount;
    @Ignore
private int mNumberOfRecipeIdChanges;
    @Ignore
private int mNumberOfIngredientIdChanges;
//endregion

和我的迁移

static final Migration MIGRATION_1_2 = new Migration(1, 2) {
    @Override
    public void migrate(@NonNull SupportSQLiteDatabase database) {
        // Create the new table
        database.execSQL("CREATE TABLE recipe_ingredients_new " +
                "(recipe INTEGER NOT NULL, ingredient INTEGER NOT NULL," + 
                "  amount REAL NOT NULL," +
                " PRIMARY KEY(recipe, ingredient), " +
                "FOREIGN KEY(recipe) REFERENCES recipes(id)" +
                " ON UPDATE NO ACTION ON DELETE CASCADE ," +
                " FOREIGN KEY(ingredient) REFERENCES ingredients(id) " +
                "ON UPDATE NO ACTION ON DELETE RESTRICT )" );
        // Copy the data
        database.execSQL(
                "INSERT INTO recipe_ingredientes_new (recipe, "+ 
                 " ingredient, amount)" +
                        " SELECT  recipe, ingredient, amount FROM 
recipe_ingredients");
        // Remove the old table
        database.execSQL("DROP TABLE recipe_ingredients");
        // Change the table name to the correct one
        database.execSQL("ALTER TABLE recipe_ingredients_new RENAME TO 
 recipe_ingredients");

    }
};