要让Android Room数据库始终从主键0开始为新的条目,您可以使用自定义的主键生成策略。以下是一个解决方法,包含代码示例:
import androidx.room.PrimaryKey
import androidx.sqlite.db.SupportSQLiteDatabase
import androidx.room.RoomDatabase
class PrimaryKeyGenerator : RoomDatabase.Callback() {
override fun onCreate(db: SupportSQLiteDatabase) {
super.onCreate(db)
// 设置主键自增序列从0开始
db.execSQL("CREATE TRIGGER IF NOT EXISTS reset_sequence " +
"AFTER INSERT ON table_name " +
"BEGIN " +
"UPDATE SQLITE_SEQUENCE SET seq = 0 WHERE name = 'table_name'; " +
"END;")
}
}
@Database(entities = [YourEntity::class], version = 1)
abstract class YourDatabase : RoomDatabase() {
companion object {
// ...
private var instance: YourDatabase? = null
fun getInstance(context: Context): YourDatabase {
if (instance == null) {
synchronized(YourDatabase::class) {
instance = Room.databaseBuilder(
context.applicationContext,
YourDatabase::class.java,
"your_database"
)
.addCallback(PrimaryKeyGenerator()) // 添加自定义的主键生成器
.build()
}
}
return instance!!
}
}
// ...
}
val database = YourDatabase.getInstance(context)
现在,每次插入新的条目时,主键序列将从0开始。请注意,您需要将上面的代码示例中的“table_name”替换为您的实际表名。