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:...