C API 连接MYSQL

 1 #include <iostream>
 2 #include <mysql.h>
 3 #include <string>
 4 
 5 #include <assert.h>
 6 
 7 
 8 int main()
 9 {
10         // MYSQL 初始化
11     MYSQL *ms_conn = mysql_init(NULL);
12     if (ms_conn == NULL)
13     {
14         std::cout << "Error: mysql_init failed." << std::endl;
15         return 0;
16     }
17     std::cout << "Info: mysql_init success." << std::endl;
18 
19     // 连接到MYSQL 数据库服务器，最后参数CLIENT_MULTI_STATEMENTS 指定SQL 可以同时多条。
20     MYSQL *ms_temp = NULL;
21     ms_temp = mysql_real_connect(ms_conn, "localhost", "root", "123456sx", 
22             "suyh", 0, NULL, CLIENT_MULTI_STATEMENTS);
23     if (ms_temp == NULL)
24     {
25         std::cout << "Error: mysql_real_connect() failed." << std::endl;
26         mysql_close(ms_conn), ms_conn = NULL;
27         return 0;
28     }
29     std::cout << "Info: mysql_real_connect() succect." << std::endl;
30 
31     std::string str_sqls = "";
32     // str_sqls += "SELECT * FROM player_data WHERE id = 100000;";
33     // str_sqls += "SELECT * FROM player_data WHERE id = 100001;";
34     str_sqls += "SELECT * FROM player_data WHERE id = 100002";
35 
36     // 执行SQL 语句
37     int res = 0;
38     res = mysql_real_query(ms_conn, str_sqls.c_str(), str_sqls.size());
39     if (res != 0)
40     {
41         std::cout << "Info: query failed, sql: " << str_sqls.c_str() << std::endl;
42         mysql_close(ms_conn), ms_conn = NULL;
43         return 0;
44     }
45     std::cout << "Info: query success." << std::endl;
46 
47     do
48     {
49         // 取出查询结果
50         MYSQL_RES *ms_res = mysql_store_result(ms_conn);
51         assert(ms_res != NULL);
52 
53         // 结果集中的字段个数
54         unsigned int field_num = mysql_num_fields(ms_res);
55         std::cout << "fileds number is " << field_num << std::endl;
56 
57         // 每个字段的结构
58         MYSQL_FIELD* field = mysql_fetch_field(ms_res);
59         assert(field != NULL);
60 
61         // 取出这个结果集中的结果
62         MYSQL_ROW row_data = NULL;    // typedef char ** MYSQL_ROW;
63         while (1)
64         {
65             row_data = mysql_fetch_row(ms_res);
66             if (row_data == NULL)
67                 break;    // 结果集中已无数据
68 
69             // 一行结果中每个字段的字符数
70             unsigned long *field_lens = mysql_fetch_lengths(ms_res);
71             assert(field_lens != NULL);
72             for (int i = 0; i < field_num; ++i)
73             {
74                 /*
75                 std::cout << "field_lens[" << i << "] = " << field_lens[i]
76                     << ", value is " << row_data[i] << std::endl;
77                 */
78                 std::cout << "field name: " << field[i].name;
79                 if (row_data[i] == NULL)
80                     std::cout << ", value is NULL" << std::endl;
81                 else
82                     // std::cout << ", value is " << row_data[i] << std::endl; 
83                     std::cout << ", value is NOT NULL" << std::endl;
84             }
85 
86             // ... // 处理结果
87         }
88     } while (mysql_next_result(ms_conn) == 0);
89 
90     mysql_close(ms_conn), ms_conn = NULL;
91     return 0;
92 }