mysql> select SQL_CALC_FOUND_ROWS id from stu limit 0,5;
+----+
| id |
+----+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
+----+
5 rows in set
mysql> select FOUND_ROWS();
+--------------+
| FOUND_ROWS() |
+--------------+
| 1006 |
+--------------+
1 row in set
SQL_CALC_FOUND_ROWS是一个标志, FOUND_ROWS() 后面是一个方法
