mysql>create
database
ssh2;
query ok,
1 row affected (0.04
sec)
mysql
>
usessh2;
database
changed
mysql
>
create
table
user
(
-> id integer
primary
key,
-> firstname varchar(200) not
null
,
-> lastname varchar(200) not
null
,
-> age integer
->
);query ok,
0 rows affected (0.46 sec)
給主鍵增加乙個自增的功能：
mysql>alter
table
user modify id integer
auto_increment ;
query ok,
1 row affected (0.28
sec)
records:
1 duplicates: 0 warnings: 0
這樣，上面的user表裡面的主鍵，id可以自增了。
給上面的主鍵id增加預設值和自增功能。
mysql>alter
table
user modify id integer
default'1
';query ok,
0 rows affected (0.16
sec)
records:
0 duplicates: 0 warnings: 0
mysql
>
alter
table
user modify id integer
auto_increment ;
query ok,
1 row affected (0.28
sec)
records:
1 duplicates: 0 warnings: 0
mysql>alter
table
user
add createtime timestamp
default
current_timestamp
;query ok,
2 rows affected (0.17
sec)
records:
2 duplicates: 0 warnings: 0
mysql設定主鍵不能為空，還要自動增長（這裡沒有設定預設值，但是預設是1，從1開始增長。），還要得到系統預設日期：
mysql>create
table
dd(
-> id int
primary
keynot
null
auto_increment,
-> name varchar(20
),
-> time timestamp
default
current_timestamp
->
);query ok,
0 rows affected (0.10
sec)
mysql
>
insert
into dd(name) values ('
fhihgifds');
query ok,
1 row affected (0.14
sec)
mysql
>
insert
into dd(name) values ('
steven');
query ok,
1 row affected (0.08
sec)
mysql
>
select
*from
dd;+
----+-----------+---------------------+
| id | name | time |+--
--+-----------+---------------------+|1
| fhihgifds |
2011-03
-2701:58:46||
2| steven |
2011-03
-2701:59:35|+
----+-----------+---------------------+
2 rows in
set (0.08
sec)
mysql
>
insert
into dd(name) values ('
anthony');
query ok,
1 row affected (0.09
sec)
mysql
>
select
*from
dd;+
----+-----------+---------------------+
| id | name | time |+--
--+-----------+---------------------+|1
| fhihgifds |
2011-03
-2701:58:46||
2| steven |
2011-03
-2701:59:35||
3| anthony |
2011-03
-2702:00:07|+
----+-----------+---------------------+
3 rows in
set (0.00
sec)
mysql
>
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