子查询返回错误

Question

我正在尝试实现子查询，但收到错误only a single result allowed。我在查询中实现错误还是语句本身错了？

搜索应返回与嵌套选择语句

中生成的代码匹配的配方名称

查询

    return db.rawQuery("select recipe_name from recipes where recipe_code in (select ingredients.recipe_code, ingredients._id from ingredients inner join kitchen on kitchen.ingredient_name = ingredients.ingredient_name)", null);

错误

 Caused by: android.database.sqlite.SQLiteException: only a single result allowed for a SELECT that is part of an expression (code 1): , while compiling: select recipe_name from recipes where recipe_code in (select ingredients.recipe_code, ingredients._id from ingredients inner join kitchen on kitchen.ingredient_name = ingredients.ingredient_name)

12-10 22：19：04.238 29209-29209 / com.example.rory.prototypev2 E / AndroidRuntime：at android.database.sqlite.SQLiteConnection.nativePrepareStatement（Native Method）

Answer 1

我认为问题在于您尝试为子查询返回多个列，并且只允许返回一列。删除成分._id

查询将返回

recipe_code, _id
  123         5

您只需要代码。