How to get multiple counts from room database?

问题

I want to return multiple counts from Room Select query in android. My query is like

Select Count(CASE WHEN x = '0' or x = '2'), Count(Case when a = '33' or a = '23') FROM my_table WHERE id=10

I want above query to return something as list which will contain values of both the above Count() function. This can be easily done using SQLite but I want to use it in room.

回答1:

You can give names to the counts and return them as a class, like:

data class MyCounts(
  @ColumnInfo(name = "first_count")
  val firstCount: Int,

  @ColumnInfo(name = "second_count")
  val secondCount: Int
)

@Dao
interface MyDao {
  @Query("SELECT COUNT(*) as first_count, COUNT(*) as second_count from my_table")
  suspend fun getMyCounts(): MyCounts
}

来源：https://stackoverflow.com/questions/62382612/how-to-get-multiple-counts-from-room-database