MySQL中的一个update的case

create database db2;
use db2;
create table t1(id int , col1 int , col2 int);
insert into t1 select 1,11,22;
insert into t1 select 2,12,33;

select * from t1;
+------+------+------+
| id   | col1 | col2 |
+------+------+------+
|    1 |   11 |   22 |
|    2 |   12 |   33 |
+------+------+------+
2 rows in set (0.00 sec)


执行下面的这个update语句
UPDATE t1 SET col1 = col1 + 1, col2 = col1;

请问最新的col1和col2数值是多少？
答案1：
1 11 11
2 12 12
答案2：
1 12 12
2 13 13


正确答案：
select * from t1; 
+------+------+------+
| id   | col1 | col2 |
+------+------+------+
|    1 |   12 |   12 |
|    2 |   13 |   13 |
+------+------+------+
2 rows in set (0.01 sec)