MYSQL C API : mysql_real_query()

 enum enum_field_types {
     MYSQL_TYPE_DECIMAL,
     MYSQL_TYPE_TINY,
     MYSQL_TYPE_SHORT,
     MYSQL_TYPE_LONG,
     MYSQL_TYPE_FLOAT,
     MYSQL_TYPE_DOUBLE,
     MYSQL_TYPE_NULL,
     MYSQL_TYPE_TIMESTAMP,
     MYSQL_TYPE_LONGLONG,
     MYSQL_TYPE_INT24,
     MYSQL_TYPE_DATE,
     MYSQL_TYPE_TIME,
     MYSQL_TYPE_DATETIME,
     MYSQL_TYPE_YEAR,
     MYSQL_TYPE_NEWDATE,
     MYSQL_TYPE_VARCHAR,
     MYSQL_TYPE_BIT,
     MYSQL_TYPE_TIMESTAMP2,
     MYSQL_TYPE_DATETIME2,
     MYSQL_TYPE_TIME2,
     MYSQL_TYPE_NEWDECIMAL=,
     MYSQL_TYPE_ENUM=,
     MYSQL_TYPE_SET=,
     MYSQL_TYPE_TINY_BLOB=,
     MYSQL_TYPE_MEDIUM_BLOB=,
     MYSQL_TYPE_LONG_BLOB=,
     MYSQL_TYPE_BLOB=,
     MYSQL_TYPE_VAR_STRING=,
     MYSQL_TYPE_STRING=,
     MYSQL_TYPE_GEOMETRY=
 }

 typedef struct st_mysql_field {
   char *name;                 /* Name of column 列名 */
   char *org_name;             /* Original column name, if an alias */
   char *table;                /* Table of column if column was a field */
   char *org_table;            /* Org table name, if table was an alias */
   char *db;                   /* Database for table */
   char *catalog;           /* Catalog for table */
   char *def;                  /* Default value (set by mysql_list_fields) */
   unsigned long length;       /* Width of column (create length) */
   unsigned long max_length;   /* Max width for selected set */
   unsigned int name_length;
   unsigned int org_name_length;
   unsigned int table_length;
   unsigned int org_table_length;
   unsigned int db_length;
   unsigned int catalog_length;
   unsigned int def_length;
   unsigned int flags;         /* Div flags */
   unsigned int decimals;      /* Number of decimals in field */
   unsigned int charsetnr;     /* Character set */
   enum enum_field_types type; /* Type of field. See mysql_com.h for types */   // 字段的mysql 数据类型
   void *extension;
 } MYSQL_FIELD;

 int    mysql_real_query(MYSQL *mysql, const char *q, unsigned long length);
     说明：执行SQL
     参数1：已初始化的MYSQL 实例；
     参数2：SQL 语句；
     参数3：SQL 语句字符数。

 MYSQL_RES *mysql_store_result(MYSQL *mysql);
     说明：对于成功检索了数据的每个查询（SELECT、SHOW、DESCRIBE、EXPLAIN、CHECK TABLE等），必须调用mysql_store_result()或mysql_use_result()
     参数：已初始化的MYSQL 实例。

 // typedef char **MYSQL_ROW;
 MYSQL_ROW mysql_fetch_row(MYSQL_RES *result);
     说明：检索一个结果集合的下一行。当在mysql_store_result()之后使用时，如果没有更多的行可检索时，mysql_fetch_row()返回NULL。当在mysql_use_result()之后使用时，当没有更多的行可检索时或如果出现一个错误，mysql_fetch_row()返回NULL。

代码范例：

 #include <iostream>
 #include <mysql.h>
 #include <string>

 #include <assert.h>

 int main()
 {
     // 1、初始化MYSQL 实例
     MYSQL *ms_conn = mysql_init(NULL);
     if (ms_conn == NULL)
     {
         std::cout << "Error: mysql_init failed." << std::endl;
         return ;
     }
     std::cout << "Info: mysql init successful." << std::endl;

     // 2、连接MYSQL 服务器
     MYSQL *ms_tmp_res = NULL;
     ms_tmp_res = mysql_real_connect(ms_conn, "localhost", "root", "123456sx",
             "suyh", , NULL, );
     if (ms_tmp_res == NULL)
     {
         std::cout << "Error: connect mysql failed: " << mysql_error(ms_conn) << std::endl;
         mysql_close(ms_conn), ms_conn = NULL;
         return ;
     }
     std::cout << "Info: mysql connect successful." << std::endl;

     // 3、执行SQL 语句
     std::string str_sqls = "";
     str_sqls += "SELECT id, account, sex, level, powers FROM player_data WHERE id = 100000 OR id = 100001 OR id = 100002";

     int res = ;
     res = mysql_real_query(ms_conn, str_sqls.c_str(), str_sqls.size());
     if (res != )
     {
         std::cout << "Error: query failed, sql: " << str_sqls.c_str() << std::endl;
         std::cout << mysql_error(ms_conn) << std::endl;
     }
     else
     {
         std::cout << "Info: query successful." << std::endl;

         // 取出SQL 语句执行的结果集
         MYSQL_RES *ms_res = mysql_store_result(ms_conn);
         if (ms_res != NULL)
         {
             // 字段个数
             unsigned int field_num = mysql_num_fields(ms_res);

             // 每个字段的数据信息
             MYSQL_FIELD* field_info = mysql_fetch_field(ms_res);
             assert(field_info != NULL);

             // 每一个字段的值存储在row_data[i] 中，基本都以字符串的形式存储。NULL 的结果 指针也是NULL。
             // 二进制数据可以通过mysql_fetch_lengths() 函数得到该字段的二进制数据长度，同样以数组形式取出，即：lens[i];
             MYSQL_ROW row_data = NULL;    // mysql.h    ---    typedef char **MYSQL_ROW;
             while ()
             {
                 row_data = mysql_fetch_row(ms_res);    // 取出下一行结果
                 if (row_data == NULL)
                     break;

                 std::cout << "##############################################" << std::endl;
                 for (int i = ; i < field_num; ++i)
                 {
                     if (row_data[i] == NULL)
                         std::cout << "field name: '" << field_info[i].name << "', values is NULL." << std::endl;
                     else
                         std::cout << "field name: '" << field_info[i].name << "', values is " << row_data[i] << std::endl;
                 }
             }
         }

         // 释放结果集
         mysql_free_result(ms_res), ms_res = NULL;
     }

     // 使用完释放系统资源
     mysql_close(ms_conn), ms_conn = NULL;

     return ;
 }