Linux 下C语言连接mysql实例详解
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<p>
<strong>Linux 下C语言连接mysql实例详解</strong></p>
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<strong>第一步:</strong></p>
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安装mysql, 参考:http://www.jb51.net/article/45034.html</p>
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<strong>第二步:</strong></p>
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</p>
<p>
安装mysql.h函数库</p>
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<code class="cpp plain">sudo apt-get install libmysqlclient-dev</code>
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执行之后就可以看到/usr/include/MySQL目录了</p>
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然后开始我们的链接.</p>
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首先看我的数据库</p>
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<code class="cpp plain">mysql> show databases;</code>
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<code class="cpp plain">+--------------------+</code>
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<code class="cpp plain">| Database |</code>
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<code class="cpp plain">+--------------------+</code>
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<code class="cpp plain">| information_schema |</code>
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<code class="cpp plain">| chat_room |</code>
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<code class="cpp plain">| mysql |</code>
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<code class="cpp plain">| mysql_shiyan |</code>
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<code class="cpp plain">| performance_schema |</code>
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<code class="cpp plain">| sys |</code>
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<code class="cpp plain">+--------------------+</code>
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<code class="cpp plain">6 rows in set (0.00 sec)</code>
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<code class="cpp plain">mysql> use chat_room;</code>
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<code class="cpp plain">Reading table information </code><code class="cpp keyword bold">for</code> <code class="cpp plain">completion of table and column names</code>
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<code class="cpp plain">You can turn off </code><code class="cpp keyword bold">this</code> <code class="cpp plain">feature to get a quicker startup with -A</code>
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<code class="cpp plain">Database changed</code>
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<code class="cpp plain">mysql> show tables;</code>
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<code class="cpp plain">+---------------------+</code>
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<code class="cpp plain">| Tables_in_chat_room |</code>
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<code class="cpp plain">+---------------------+</code>
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<code class="cpp plain">| user_message |</code>
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<code class="cpp plain">+---------------------+</code>
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<code class="cpp plain">1 row in set (0.00 sec)</code>
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<code class="cpp plain">mysql> select * from user_message;</code>
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<code class="cpp plain">+------+-------+--------+</code>
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<code class="cpp plain">| ID | name | passwd |</code>
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<code class="cpp plain">+------+-------+--------+</code>
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<code class="cpp plain">| 1 | linux | linux |</code>
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<code class="cpp plain">| 2 | lyt | lyt |</code>
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<code class="cpp plain">+------+-------+--------+</code>
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<code class="cpp plain">2 rows in set (0.00 sec)</code>
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可以看到,我在chat_room数据库中有user_message这张表,我们现在要做的就是读出这张表里的数据.</p>
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直接上代码</p>
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<code class="sql plain">#include<stdio.h></code>
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<code class="sql plain">#include<stdlib.h></code>
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<code class="sql plain">#include<errno.h></code>
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<code class="sql plain">#include<mysql/mysql.h></code>
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<code class="sql keyword">int</code> <code class="sql plain">main(void)</code>
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<code class="sql plain">{</code>
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<code class="sql spaces"> </code><code class="sql keyword">char</code> <code class="sql plain">*sql;</code>
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<code class="sql spaces"> </code><code class="sql plain">sql=</code><code class="sql string">"SELECT * FROM user_message;"</code><code class="sql plain">;</code>
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<code class="sql spaces"> </code><code class="sql keyword">int</code> <code class="sql plain">res;//执行sql语句后的返回标志</code>
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<code class="sql spaces"> </code><code class="sql plain">MYSQL_RES *res_ptr;//指向查询结果的指针</code>
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<code class="sql spaces"> </code><code class="sql plain">MYSQL_FIELD *field;//字段结构指针</code>
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<code class="sql spaces"> </code><code class="sql plain">MYSQL_ROW result_row;//按行返回查询信息</code>
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<code class="sql spaces"> </code><code class="sql keyword">int</code> <code class="sql plain">row,</code><code class="sql keyword">column</code><code class="sql plain">;//查询返回的行数和列数</code>
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<code class="sql spaces"> </code><code class="sql plain">MYSQL *conn;//一个数据库链接指针</code>
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<code class="sql spaces"> </code><code class="sql keyword">int</code> <code class="sql plain">i,j;</code>
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<code class="sql spaces"> </code><code class="sql plain">//初始化连接句柄</code>
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<code class="sql spaces"> </code><code class="sql plain">conn = mysql_init(</code><code class="sql color1">NULL</code><code class="sql plain">);</code>
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<code class="sql spaces"> </code><code class="sql plain">if(conn == </code><code class="sql color1">NULL</code><code class="sql plain">) { //如果返回</code><code class="sql color1">NULL</code><code class="sql plain">说明初始化失败</code>
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<code class="sql spaces"> </code><code class="sql plain">printf(</code><code class="sql string">"mysql_init failed!\n"</code><code class="sql plain">);</code>
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<code class="sql spaces"> </code><code class="sql keyword">return</code> <code class="sql plain">EXIT_FAILURE;</code>
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<code class="sql spaces"> </code><code class="sql plain">}</code>
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<code class="sql spaces"> </code><code class="sql plain">//进行实际连接</code>
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<code class="sql spaces"> </code><code class="sql plain">//参数 conn连接句柄,host mysql所在的主机或地址,</code><code class="sql color2">user</code><code class="sql plain">用户名,passwd密码,database_name数据库名,后面的都是默认</code>
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<code class="sql spaces"> </code><code class="sql plain">conn = mysql_real_connect(conn,</code><code class="sql string">"localhost"</code><code class="sql plain">,</code><code class="sql string">"lyt"</code><code class="sql plain">,</code><code class="sql string">""</code><code class="sql plain">,</code><code class="sql string">"chat_room"</code><code class="sql plain">,0,</code><code class="sql color1">NULL</code><code class="sql plain">,0);</code>
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<code class="sql spaces"> </code><code class="sql plain">if (conn) {</code>
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<code class="sql spaces"> </code><code class="sql plain">printf(</code><code class="sql string">"Connection success!\n"</code><code class="sql plain">);</code>
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<code class="sql spaces"> </code><code class="sql plain">} </code><code class="sql keyword">else</code> <code class="sql plain">{</code>
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<code class="sql spaces"> </code><code class="sql plain">printf(</code><code class="sql string">"Connection failed!\n"</code><code class="sql plain">);</code>
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<code class="sql spaces"> </code><code class="sql plain">}</code>
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<code class="sql spaces"> </code><code class="sql plain">mysql_query(conn,</code><code class="sql string">"set names gbk"</code><code class="sql plain">);//防止乱码。设置和数据库的编码一致就不会乱码</code>
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<code class="sql spaces"> </code><code class="sql plain">res = mysql_query(conn,sql);//正确返回0</code>
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<code class="sql spaces"> </code><code class="sql plain">if(res) {</code>
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<code class="sql spaces"> </code><code class="sql plain">perror(</code><code class="sql string">"my_query"</code><code class="sql plain">);</code>
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<code class="sql spaces"> </code><code class="sql plain">mysql_close(conn);</code>
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<code class="sql spaces"> </code><code class="sql plain">exit(0);</code>
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<code class="sql spaces"> </code><code class="sql plain">} </code><code class="sql keyword">else</code><code class="sql plain">{</code>
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<code class="sql spaces"> </code><code class="sql plain">//把查询结果给res_ptr</code>
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<code class="sql spaces"> </code><code class="sql plain">res_ptr = mysql_store_result(conn);</code>
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<code class="sql spaces"> </code><code class="sql plain">//如果结果不为空,则输出</code>
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<code class="sql spaces"> </code><code class="sql plain">if(res_ptr) {</code>
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<code class="sql spaces"> </code><code class="sql keyword">column</code> <code class="sql plain">= mysql_num_fields(res_ptr);</code>
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<code class="sql spaces"> </code><code class="sql plain">row = mysql_num_rows(res_ptr);</code>
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<code class="sql spaces"> </code><code class="sql plain">printf(</code><code class="sql string">"查到%d行\n"</code><code class="sql plain">,row);</code>
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<code class="sql spaces"> </code><code class="sql plain">//输出结果的字段名</code>
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<code class="sql spaces"> </code><code class="sql keyword">for</code><code class="sql plain">(i = 0;field = mysql_fetch_field(res_ptr);i++) {</code>
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<code class="sql spaces"> </code><code class="sql plain">printf(</code><code class="sql string">"%10s"</code><code class="sql plain">,field-></code><code class="sql keyword">name</code><code class="sql plain">);</code>
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<code class="sql spaces"> </code><code class="sql plain">}</code>
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<code class="sql spaces"> </code><code class="sql plain">puts(</code><code class="sql string">""</code><code class="sql plain">);</code>
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<code class="sql spaces"> </code><code class="sql plain">//按行输出结果</code>
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<code class="sql spaces"> </code><code class="sql keyword">for</code><code class="sql plain">(i = 1;i < row+1;i++){</code>
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<code class="sql spaces"> </code><code class="sql plain">result_row = mysql_fetch_row(res_ptr);</code>
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<code class="sql spaces"> </code><code class="sql keyword">for</code><code class="sql plain">(j = 0;j< </code><code class="sql keyword">column</code><code class="sql plain">;j++) {</code>
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<code class="sql spaces"> </code><code class="sql plain">printf(</code><code class="sql string">"%10s"</code><code class="sql plain">,result_row);</code>
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<code class="sql spaces"> </code><code class="sql plain">}</code>
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<code class="sql spaces"> </code><code class="sql plain">puts(</code><code class="sql string">""</code><code class="sql plain">);</code>
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<code class="sql spaces"> </code><code class="sql plain">}</code>
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<code class="sql spaces"> </code><code class="sql plain">}</code>
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<code class="sql spaces"> </code><code class="sql plain">}</code>
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<code class="sql spaces"> </code><code class="sql plain">//退出前关闭连接</code>
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<code class="sql spaces"> </code><code class="sql plain">mysql_close(conn);</code>
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<code class="sql spaces"> </code><code class="sql keyword">return</code> <code class="sql plain">0;</code>
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<code class="sql plain">}</code>
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结果</p>
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<code class="bash plain">gcc -o mysql a.c -L</code><code class="bash plain">/usr/lib/mysql</code> <code class="bash plain">-lmysqlclient</code>
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<code class="bash plain">.</code><code class="bash plain">/mysql</code>
</div>
<div class="line number3 index2 alt2">
<code class="bash plain">Connection success!</code>
</div>
<div class="line number4 index3 alt1">
<code class="bash plain">查到2行</code>
</div>
<div class="line number5 index4 alt2">
<code class="bash spaces"> </code><code class="bash plain">ID name </code><code class="bash functions">passwd</code>
</div>
<div class="line number6 index5 alt1">
<code class="bash spaces"> </code><code class="bash plain">1 linux linux</code>
</div>
<div class="line number7 index6 alt2">
<code class="bash spaces"> </code><code class="bash plain">2 lyt lyt</code>
</div>
</div>
</td>
</tr></tbody></table>
</div>
</div>
<div class="codetool" id="codetool">
<div class="code_n">
<textarea></textarea>
</div>
</div>
</div>
<p>
注释写的相当清楚,有什么不清楚的可以给我留言,大家一块学习!</p>
<p>
原文链接:http://blog.csdn.net/baidu_35085676/article/details/52160133</p>
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