為什麼第二個語法沒寫from emp反而沒有Error
mysql> select ename, sal ,deptno
-> from emp
-> where deptno=(select deptno
->               from emp
->               where ename like '%t%');
ERROR 1242 (21000): Subquery returns more than 1 row
mysql> select ename, sal ,deptno
-> from emp
-> where deptno=(select deptno
-> 		     where ename like '%t%');
+--------+---------+--------+
| ename  | sal     | deptno |
+--------+---------+--------+
| SMITH     |  800.00   |     20 |
| MARTIN | 1250.00 |     30 |
| SCOTT     | 3000.00 |     20 |
| TURNER | 1500.00 |     30 |
+--------+---------+--------+
4 rows in set (0.00 sec)