2 掌握MySQL的SELECT语法

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2.1 阅读文档，找到SELECT的语法

http://dev.mysql.com/doc/refman/5.1/zh/sql-syntax.html#select

2.2 读SELECT的说明文档

2.3 实践文档提及的SELECT子句的功能，并提交自己的练习SQL和结果

mysql> select * from students;+----+-------+----------+------------+| id | name  | addresss | year       |+----+-------+----------+------------+|  1 | allen | Beijing  | 1980-01-02 ||  2 | pual  | Shanghai | 1980-01-02 ||  3 | john  | dalian   | 1980-01-02 |+----+-------+----------+------------+3 rows in set (0.00 sec)

mysql> select name,year from students;+-------+------------+| name  | year       |+-------+------------+| allen | 1980-01-02 || pual  | 1980-01-02 || john  | 1980-01-02 |+-------+------------+3 rows in set (0.00 sec)

mysql> select concat(name, ',', year) string from students order by string;+------------------+| string           |+------------------+| allen,1980-01-02 || john,1980-01-02  || pual,1980-01-02  |+------------------+3 rows in set (0.00 sec

mysql> select t1.name, t2.name from students as t1, teachers as t2 where t1.name = t2.name;+------+------+| name | name |+------+------+| john | john |+------+------+1 row in set (0.00 sec)

mysql> select name, year, id from students order by name, year;+-------+------------+----+| name  | year       | id |+-------+------------+----+| allen | 1980-01-02 |  1 || john  | 1980-01-02 |  3 || pual  | 1980-01-02 |  2 |+-------+------------+----+3 rows in set (0.00 sec)

mysql> select name, year, id from students order by name DESC, year;+-------+------------+----+| name  | year       | id |+-------+------------+----+| pual  | 1980-01-02 |  2 || john  | 1980-01-02 |  3 || allen | 1980-01-02 |  1 |+-------+------------+----+3 rows in set (0.00 sec)

mysql> select name, count(year), id from students group by id;+-------+-------------+----+| name  | count(year) | id |+-------+-------------+----+| allen |           1 |  1 || pual  |           1 |  2 || john  |           1 |  3 |+-------+-------------+----+3 rows in set (0.00 sec)

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