mysql的select查询语句

1.简单查询

mysql> select * from students;
+------------+----------+------+------+
| id         | sname    | sex  | tid  |
+------------+----------+------+------+
| 0000000001 | orna     | 男   | NULL |
| 0000000002 | luscy    | 女   | NULL |
| 0000000003 | wangwu   | 男   | NULL |
| 0000000020 | zhangsan | 男   | NULL |
+------------+----------+------+------+
4 rows in set (0.00 sec)


mysql> select id,ifnull(sname,'无') name from students;
+------------+----------+
| id         | name     |
+------------+----------+
| 0000000001 | orna     |
| 0000000002 | luscy    |
| 0000000003 | wangwu   |
| 0000000020 | zhangsan |
+------------+----------+
4 rows in set (0.00 sec)

   mysql> select * from students where sname like 'o%';
   +------------+-------+------+------+
   | id | sname | sex | tid |
  +------------+-------+------+------+
  | 0000000001 | orna | 男 | NULL |
  +------------+-------+------+------+
  1 row in set (0.00 sec)

2.排序

mysql> select * from students order by sname desc;
+------------+----------+------+------+
| id         | sname    | sex  | tid  |
+------------+----------+------+------+
| 0000000020 | zhangsan | 男   | NULL |
| 0000000003 | wangwu   | 男   | NULL |
| 0000000001 | orna     | 男   | NULL |
| 0000000002 | luscy    | 女   | NULL |
+------------+----------+------+------+
4 rows in set (0.00 sec)

mysql> select * from students order by sname desc limit 1;
+------------+----------+------+------+
| id         | sname    | sex  | tid  |
+------------+----------+------+------+
| 0000000020 | zhangsan | 男   | NULL |
+------------+----------+------+------+
1 row in set (0.00 sec)