MySQL Query 请教

Example code
SQL code:

create table t(idx int,cname varchar(30));
insert into t values(1,'a');
insert into t values(2,'b');
insert into t values(3,'c');




select * from t的结果这样
SQL code:

mysql> select * from t;
+------+-------+
| idx | cname |
+------+-------+
| 1 | a |
| 2 | b |
| 3 | c |
+------+-------+




怎么才能得到这种结果？
SQL code:

+------+-------+-------+
| idx | cname |countnum|
+------+-------+-------+
| 1 | a |3 |
| 2 | b |3 |
| 3 | c |3 |
+------+-------+-------+



countnum 是这张表的总记录数

SQL Server和oracle都可以用Row_number来得到，
MySQL 如何得到？

谢谢

---

mysql没有Row_number之类的函数，只有通过间接方法得到

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或者这个效率会略有差异。

SQL code:
mysql> select t.*,a.countnum
-> from t,(select count(*) as countnum from t) a;
+------+-------+----