用MySQL命令对表和相关表结构进行修改-Mysql Tutorial-php.cn

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用MySQL命令对表和相关表结构进行修改

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Jun 07, 2016 pm 04:11 PM

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在实际的操作中有时我们会遇到对数据库表与数据库进行删除与修改的情况，以下的文章就是针对这一情况给出的相关的解答方案，即使用MySQL命令对一些表正确进行修改和表结构的修改。使用MySQL命令对表的修改与表结构修改： 1、增加一列：如在前面例子中的my

在实际的操作中有时我们会遇到对数据库表与数据库进行删除与修改的情况，以下的文章就是针对这一情况给出的相关的解答方案，即使用MySQL命令对一些表正确进行修改和表结构的修改。

使用MySQL命令对表的修改与表结构修改：

1、增加一列：

如在前面例子中的mytable表中增加一列表示是否单身single:

<ol class="dp-xml"><li class="alt">MySQL<span><span class="tag">></span><span> alter table mytable add column single char(1); </span></span>
</li></ol>

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2、修改记录
将abccs的single记录修改为“y”：

<ol class="dp-xml"><li class="alt">MySQL<span><span class="tag">></span><span> update mytable set </span><span class="attribute">single</span><span>=</span><span class="attribute-value">'y'</span><span> where </span><span class="attribute">name</span><span>=</span><span class="attribute-value">'abccs'</span><span>; </span></span>
</li></ol>

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现在来看看发生了什么：

<ol class="dp-xml">
<li class="alt">MySQL<span><span class="tag">></span><span> select * from mytable;   </span></span>
</li>
<li><span>+----------+------+------------+-----------+--------+   </span></li>
<li class="alt"><span>| name | sex | birth | birthaddr | single |   </span></li>
<li><span>+----------+------+------------+-----------+--------+   </span></li>
<li class="alt"><span>| abccs|f | 1977-07-07 | china | y |   </span></li>
<li><span>| mary |f | 1978-12-12 | usa | NULL |   </span></li>
<li class="alt"><span>| tom |m | 1970-09-02 | usa | NULL |   </span></li>
<li><span>+----------+------+------------+-----------+--------+ </span></li>
</ol>

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3、增加记录

前面已经讲过如何增加一条记录，为便于查看，重复与此：

<ol class="dp-xml">
<li class="alt">MySQL<span><span class="tag">></span><span> insert into mytable   </span></span>
</li>
<li>
<span>-</span><span class="tag">></span><span> values ('abc','f','1966-08-17','china','n');   </span>
</li>
<li class="alt"><span>Query OK, 1 row affected (0.05 sec)  </span></li>
</ol>

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查看一下：

<ol class="dp-xml">
<li class="alt">MySQL<span><span class="tag">></span><span> select * from mytable;   </span></span>
</li>
<li><span>+----------+------+------------+-----------+--------+   </span></li>
<li class="alt"><span>| name | sex | birth | birthaddr | single |   </span></li>
<li><span>+----------+------+------------+-----------+--------+   </span></li>
<li class="alt"><span>| abccs|f | 1977-07-07 | china | y |   </span></li>
<li><span>| mary |f | 1978-12-12 | usa | NULL |   </span></li>
<li class="alt"><span>| tom |m | 1970-09-02 | usa | NULL |   </span></li>
<li><span>| abc |f | 1966-08-17 | china | n |   </span></li>
<li class="alt"><span>+----------+------+------------+-----------+--------+ </span></li>
</ol>

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3、删除记录

用如下MySQL命令删除表中的一条记录：

<ol class="dp-xml"><li class="alt">MySQL<span><span class="tag">></span><span> delete from mytable where </span><span class="attribute">name</span><span>=</span><span class="attribute-value">'abc'</span><span>;  </span></span>
</li></ol>

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DELETE从表中删除满足由where给出的条件的一条记录。

再显示一下结果：

<ol class="dp-xml">
<li class="alt">MySQL<span><span class="tag">></span><span> select * from mytable;   </span></span>
</li>
<li><span>+----------+------+------------+-----------+--------+   </span></li>
<li class="alt"><span>| name | sex | birth | birthaddr | single |   </span></li>
<li><span>+----------+------+------------+-----------+--------+   </span></li>
<li class="alt"><span>| abccs|f | 1977-07-07 | china | y |   </span></li>
<li><span>| mary |f | 1978-12-12 | usa | NULL |   </span></li>
<li class="alt"><span>| tom |m | 1970-09-02 | usa | NULL |   </span></li>
<li><span>+----------+------+------------+-----------+--------+ </span></li>
</ol>

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4、删除表：

MySQL> drop table ****(表1的名字)，***表2的名字;

可以删除一个或多个表，小心使用。

5、数据库的删除：

MySQL> drop database 数据库名;

小心使用。

6、数据库的备份：

退回到DOS：

<ol class="dp-xml">
<li class="alt">MySQL<span><span class="tag">></span><span> quit   </span></span>
</li>
<li>
<span>d:</span>MySQL<span>bin  </span>
</li>
</ol>

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使用如下MySQL命令对数据库abccs进行备份：

<ol class="dp-xml"><li class="alt">MySQL<span>dump --opt abccs</span><span>>abccs.dbb  </span>
</li></ol>

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abccs.dbb就是你的数据库abccs的备份文件。

7、用批处理方式使用MySQL:

首先建立一个批处理文件mytest.sql,内容如下：

<ol class="dp-xml">
<li class="alt"><span><span>use abccs;   </span></span></li>
<li><span>select * from mytable;   </span></li>
<li class="alt">
<span>select name,sex from mytable where </span><span class="attribute">name</span><span>=</span><span class="attribute-value">'abccs'</span><span>; </span>
</li>
</ol>

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在DOS下运行如下命令：

<ol class="dp-xml"><li class="alt">d:MySQL<span>bin </span>MySQL<span> </span><span class="tag"><span> </span><span>mytest.sql  </span></span>
</li></ol>

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在屏幕上会显示执行结果。

如果想看结果，而输出结果很多，则可以用这样的MySQL命令：

<ol class="dp-xml"><li class="alt">MySQL<span> </span><span class="tag"><span> </span><span>mytest.sql | more </span></span>
</li></ol>

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我们还可以将结果输出到一个文件中：

<ol class="dp-xml"><li class="alt">MySQL<span> </span><span class="tag"><span> </span><span class="tag-name">mytest.sql</span><span> </span><span>> mytest.out </span></span>
</li></ol>

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加索引549830479

<ol class="dp-xml">
<li class="alt">MySQL<span><span class="tag">></span><span> alter table tablename change depno depno int(5) not null;  </span></span>
</li>
<li>MySQL<span class="tag">></span><span> alter table tablename add index 索引名 (字段名1[，字段名2 …]);  </span>
</li>
<li class="alt">MySQL<span class="tag">></span><span> alter table tablename add index emp_name (name); </span>
</li>
</ol>

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加主关键字的索引549830479

<ol class="dp-xml"><li class="alt">MySQL<span><span class="tag">></span><span> alter table tablename add primary key(id); </span></span>
</li></ol>

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加唯一限制条件的索引549830479

<ol class="dp-xml"><li class="alt">MySQL<span><span class="tag">></span><span> alter table tablename add unique emp_name2(cardnumber); </span></span>
</li></ol>

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删除某个索引549830479

<ol class="dp-xml"><li class="alt">MySQL<span><span class="tag">></span><span>alter table tablename drop index emp_name; </span></span>
</li></ol>

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修改表：549830479

增加字段：549830479

<ol class="dp-xml"><li class="alt">MySQL<span><span class="tag">></span><span> ALTER TABLE table_name ADD field_name field_type; </span></span>
</li></ol>

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修改原字段名称及类型：549830479

<ol class="dp-xml"><li class="alt">MySQL<span><span class="tag">></span><span> ALTER TABLE table_name CHANGE old_field_name new_field_name field_type; </span></span>
</li></ol>

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删除字段：549830479

<ol class="dp-xml"><li class="alt">MySQL<span><span class="tag">></span><span> ALTER TABLE table_name DROP field_name; </span></span>
</li></ol>

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PS;修改字段属性

<ol class="dp-xml"><li class="alt"><span><span>ALTER TABLE tableName MODIFY cloumnName DATETIME; </span></span></li></ol>

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以上的相关内容就是对使用MySQL命令对表的修改与表结构修改.的介绍，望你能有所收获。

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