1.查询指定字段
this.list(WrapperLambdaQuery(objectTable.class).select(要查询的字段).eq(),Object::toString);
List<String> itemIds = this.list(Wrappers.lambdaQuery(ItemInfo.class)
.select(ItemInfo::getId)
.eq(ItemInfo::getItemCode, item.getItemCode()), Object::toString);
2.查询指定第一个对象
String id= this.list(Wrappers.lambdaQuery(ItemInfo.class).select(ItemInfo::getId)
.eq(ItemInfo::getItemCode, item.getItemCode())).stream().findFirst().orElse(null);
3.范围IN查询
List<String> itemIds = lists.stream().map(ItemInfo::getId).collect(Collectors.toList());
List<Student> students= this.list(Wrappers.lambdaQuery(Student.class).in(Class::getStudent, batches).orderByDesc(Student::getCreateTime));
4根据条件更新表里某些字段
this.update(Wrappers.lambdaUpdate(OrderInfo.class)
.set(OrderInfo::getOrderStatus, "1")
.set(OrderInfo::getId, orderInfo.getId() )
.eq(OrderInfo::getId, "10020")