練習：
1、在yg_tab表裏添加名id的字段，在所有字段的上方，爲主鍵字段且有自動增長功能。把表中的name和sex字段設置爲index字段。
在部門字段下方添加mail字段默認值是[email protected]。
在id字段下添加名爲yg_id字段，字段值不允許重複，
在mail字段下方添加loves字段保存員工的愛好 默認愛好 IT,film
2、查看錶結構看設置是否正確
3、向表中插入3條新的員式記錄
4、查看記錄是否插入成功
5、刪除表裏所有字段的索引屬性
6、查看錶結構是否刪除成功。
7、複製當前表新表名爲 newuser
8、刪除yg_tab表中所有記錄
mysql> alter table yg_tab modify id int(2) not null primary key auto_increment; ///在yg_tab表中添id字段在最上方,字段類型int(2) //不允許空值not null //設置爲主鍵primary key //自動增長功能 auto_increment Query OK, 3 rows affected (0.00 sec) Records: 3 Duplicates: 0 Warnings: 0 |
| mysql> select * from yg_tab; //查看yg_tab表的內容。 +----+------+--------+------+-----------+----------+------+------------+---------+ | id | name | gender | age | entrytime | position | work | department | work_id | +----+------+--------+------+-----------+----------+------+------------+---------+ | 1 | tom | boy | 23 | 2013 | staff | IT | plan | 100 | | 2 | jea | gril | 18 | 2012 | manager | chef | finance | 100 | | 3 | kek | boy | 24 | 2010 | staff | driv | personnel | 100 | +----+------+--------+------+-----------+----------+------+------------+---------+ 3 rows in set (0.00 sec) |
| mysql> create index name on yg_tab(name); //爲yg_tab表的name字段設置index Query OK, 3 rows affected (0.00 sec) Records: 3 Duplicates: 0 Warnings: 0 //設置name字段爲索引，索引名爲name |
| mysql> create index gender on yg_tab(name); Query OK, 3 rows affected (0.00 sec) Records: 3 Duplicates: 0 Warnings: 0 //同上。 |
| mysql> alter table yg_tab add loves set("IT","film","game") default "IT,film"; Query OK, 3 rows affected (0.00 sec) Records: 3 Duplicates: 0 Warnings: //添加字段loves， //多選 set("IT","film","game") //默認值爲"IT,film" |
| mysql> alter table yg_tab modify mail char(15) not null ; //添加yg_tab表中的mail字段 //指定寬度爲15字節。 //不允許爲空值 not null Query OK, 3 rows affected (0.01 sec) Records: 3 Duplicates: 0 Warnings: 0. |
| mysql>insert into yg_tab values ("6","anmi","gril","24","2013","manager","chef","finance","106","[email protected]","film"); //添加記錄。 |
| mysql> select * from yg_tab; +----+------+--------+-----+-----------+----------+------+------------+---------+-----------------+---------+ | id | name | gender | age | entrytime | position | work | department | work_id | mail | loves | +----+------+--------+-----+-----------+----------+------+------------+---------+-----------------+---------+ | 1 | tom | boy | 23 | 2013 | staff | IT | plan | 100 | [email protected] | IT,film | | 2 | jea | gril | 18 | 2012 | manager | chef | finance | 100 | [email protected] | IT,film | | 3 | kek | boy | 24 | 2010 | staff | driv | personnel | 100 | [email protected] | IT,film | | 4 | heh | boy | 18 | 2011 | staff | IT | plan | 101 | [email protected] | IT | | 5 | lia | boy | 34 | 2003 | manager | chef | finance | 103 | [email protected] | film | | 6 | anm | gril | 24 | 2013 | manager | chef | finance | 106 | [email protected] | film | +----+------+--------+-----+-----------+----------+------+------------+---------+-----------------+---------+ 6 rows in set (0.00 sec) |
| mysql> create table newuser select * from ygdb.yg_tab; //複製ygdb.yg_tab，新表名爲newuser Query OK, 6 rows affected (0.00 sec) Records: 6 Duplicates: 0 Warnings: 0 |
| mysql> show tables; +----------------+ | Tables_in_ygdb | +----------------+ | newuser | | yg_tab | +----------------+ 2 rows in set (0.00 sec |
| mysql> alter table yg_tab modify id int(2) not null; //yg_tab表中的id字段保留類型，修改不能爲空值 Query OK, 6 rows affected (0.00 sec) Records: 6 Duplicates: 0 Warnings: 0 |
| mysql> alter table yg_tab drop primary key; //刪除yg_tab表的主鍵 Query OK, 6 rows affected (0.00 sec) Records: 6 Duplicates: 0 Warnings: 0 |
| mysql> delete from yg_tab; //刪除yg_tab表的所有內容 Query OK, 6 rows affected (0.00 sec) |