Mysql数据库学习心得(4)
10.表的数据更新
(1)一次修改一个字段,再次注意语法。文本需要加引号但数字不要。
mysql>update table01 set field03='new info'swheresfield01=1;
Query OK, 1 row affected (0.00 sec)
(2)一次改变多个字段,记住在每一个更新的字段间用逗号隔开。
mysql>update table01 set field04=19991022, field05=062218swheresfield01=1;
Query OK, 1 row affected (0.00 sec)
(3)一次更新多个数据
mysql>update table01 set field05=152901swheresfield04>19990101;
Query OK, 3 rows affected (0.00 sec)
11.删除数据
mysql>delete from table01swheresfield01=3;
Query OK, 1 row affected (0.00 sec)
12.导入数据库表
(1)创建.sql文件
(2)先产生一个库如auction.c:mysqlin>mysqladmin -u root -p creat auction,会提示输入密码,然后成功创建。
(3)导入auction.sql文件
c:mysqlin>mysql -u root -p auction auction.sql。
通过以上操作,就可以创建了一个数据库auction以及其中的一个表auction。
13.mysql数据库的授权
mysql>grant select,insert,delete,create,drop
on *.* (或test.*/user.*/..)
to用户名@localhost
identified by '密码';
如:新建一个用户帐号以便可以访问数据库,需要进行如下操作:
mysql> grant usage
-> ON test.*
-> TO testuser@localhost;
Query OK, 0 rows affected (0.15 sec)
此后就创建了一个新用户叫:testuser,这个用户只能从localhost连接到数据库并可以连接到test数据库。下一步,我们必须指定 testuser这个用户可以执行哪些操作:
mysql> GRANT select, insert, delete,update
-> ON test.*
-> TO testuser@localhost;
Query OK, 0 rows affected (0.00 sec)
此操作使testuser能够在每一个test数据库中的表执行SELECT,INSERT和DELETE以及UPDATE查询操作。现在我们结束操作并退出MySQL客户 程序:
mysql> exit
Bye
14.授权MySQL用户密码
MySQL数据库的默认用户名为"root"(MS SQL Server的sa相似),密码默认为空。在DOS提示符(注意,不是mysql提示符)下输入
c:mysqlin>"mysqladmin -u root -p password newpassword
回车后会提示你输入原来的密码,由于原来密码为空,直接回车,root用户的密码便改为"newpassword"了。

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