## 自動fetch ```java /** * 演示自動fetch,類似orm，但不同于orm，CRUD在ORM概念下過于復雜， * BeetlSQL的fetch沒有那么多復雜概念，僅僅是加載對象后看看還有沒有需要再加載的對象 * * * @author xiandafu */ public class S5Fetch { SQLManager sqlManager; public S5Fetch(SQLManager sqlManager) { this.sqlManager = sqlManager; } public static void main(String[] args) throws Exception { //為了簡單起見，倆個sqlManager都來自同一個數據源，實際是不同數據庫，甚至是NOSQL SQLManager sqlManager = SampleHelper.init(); S5Fetch fetch = new S5Fetch(sqlManager); fetch.fetchOne(); fetch.fetchMany(); } /** * */ public void fetchOne(){ UserData user = sqlManager.unique(UserData.class,1); System.out.println(user.getDept()); //fetchOne 會合并查詢提高性能 List<UserData> users = sqlManager.all(UserData.class); System.out.println(users.get(0).getDept()); } public void fetchMany(){ DepartmentData dept = sqlManager.unique(DepartmentData.class,1); System.out.println(dept.getUsers()); } /** * 用戶數據使用"a" sqlmanager */ @Data @Table(name="user") @Fetch public static class UserData { @Auto private Integer id; private String name; private Integer departmentId; @FetchOne("departmentId") private DepartmentData dept; } /** * 部門數據使用"b" sqlmanager */ @Data @Table(name="department") @Fetch public static class DepartmentData { @Auto private Integer id; private String name; @FetchMany("departmentId") private List<UserData> users; } } ```