Java QueryWrapper基本用法

//根据条件查询一条数据，多了会报错  
public R<Family> queryMemberId(String meberId) {
  Family family = familyService.getOne(new QueryWrapper<Family>().eq("member_id", meberId));
  return R.data(family);
}
//根据指定条件返回list
public R<List<Family>> treeList(String book_id) {
  List<Family> familyList = familyService.list(new QueryWrapper<Family>().eq("book_id", book_id));
  return R.data(buildTree(familyList));
}

//查询指定列，返回list
public R<List<Family>> select() {
  List<Family> list = familyService.list(new QueryWrapper<Family>().select("id", "name"));
  return R.data(list);
}

public R<JSONObject> listByFamily(Long id) {
  JSONObject jsonObject = new JSONObject();
  Family family = familyService.getById(id);
  //将第一个表中的数据存储到json中
  jsonObject.set("family", family);
  List<Deed> list = deedService.list(new QueryWrapper<Deed>().eq("family_id", id));
  //将第二个表中的数据存储到json中
  jsonObject.set("list", list);
  return R.data(jsonObject);
}