房间：如何基于复合主键进行查询？

Question

Room 可以使用复合主键进行查询吗？

@Entity(
    tableName = "market_cap",
    primaryKeys = ["assetId", "timestamp"]
)
data class MarketCapDataEntity(
    val assetId: String,
    val timestamp: Long,
    val price: Double
)

假设我想按主键执行查询，如下所示？

@Query("SELECT * FROM market_cap WHERE primaryKeys = :compositeKey")
suspend fun getMarketCapByAssetId(compositeKey: String): List<MarketCapDataEntity>

Answer 1

您需要在 SQL 查询中指定主键的每个组成部分，而不是尝试使用单个组合键

@Entity(
    tableName = "market_cap",
    primaryKeys = ["assetId", "timestamp"]
)
data class MarketCapDataEntity(
    val assetId: String,
    val timestamp: Long,
    val price: Double
)

@Dao
interface MarketCapDao {
    @Query("SELECT * FROM market_cap WHERE assetId = :assetId AND timestamp = :timestamp")
    suspend fun getMarketCapByAssetIdAndTimestamp(assetId: String, timestamp: Long): MarketCapDataEntity?
}