<How to select from database with "where" paramete...

# stackoverflow

[user]

How to select from database with "where" parameter SpringBoot?
I would like to get one single entry from database. I have such entry model:
@Table("USERS")
data class User(@Id val id: String?, val login: String, val password: String)

and such controller:
@RestController
class MessageResource(val service: MessageService) {
@GetMapping
fun index(): List = service.findMessages()

@PostMapping
fun post(@RequestBody user: User) {
service.post(user)
}

@GetMapping("/user")
fun getByLogin(@RequestParam("login") login:...