if的用法：
mysql> select if(10>9,10,9) as bigger from dual;
+--------+
| bigger |
+--------+
| 10 |
+--------+
left()和right()的用法：
mysql> select left(\'abcdeft\',4) a,right(\'abcdeft\',4) b;
+------+------+
| a | b |
+------+------+
| abcd | deft |
+------+------+
with rollup的用法：
select substr(tDeliverdate,1,10) riqi,sum(dSalesPrice) sale_amount from test.sale_order_detail group by riqi with rollup;
+------------+-------------+
| riqi | sale_amount |
+------------+-------------+
| 2014-12-31 | 0.300000 |
| 2015-01-17 | 240.000000 |
| NULL | 240.300000 |
+------------+-------------+