Linux-MySql

• MySql
  • 1:连接

    • #include <mysql.h>
      MYSQL *mysql_init(MYSQL *);
      MYSQL *mysql_real_connect(MYSQL *connection,const char *server_host,......);
      void mysql_close(MYSQL *connection);
      int mysql_options(MYSQL* connection, enum option_to_set const char* argument);

  • 2:错误处理
    • //错误处理函数
    • unsigned int mysql_errno(MYSQL *connection); 
    • char *mysql_error(MYSQL *connection); 
  • 3:执行SQL语句

    • //success 0
      int mysql_query(MYSQL *connection, const char *query); 
      my_ulonglong mysql_affected_rows(MYSQL *connection);

  • 4.返回数据的语句

    • //一次提取所有的数据
      MYSQL_RES *mysql_store_result(MYSQL *connection);
      //返回记录的条目
      my_ulonglong mysql_num_rows(MYSQL_RES* result);
      //从mysql_store_result中得到的结构中提取一行
      MYSQL_ROW mysql_fetch_row(MYSQL_RES *result);
      //在结果集中跳转，设置将被下一个mysql_fetch_row操作返回的行
      void mysql_data_seek(MYSQL_RES *result,my_ulonglong offset);
      //返回一个偏移值，不是行号，不能用于mysql_data_seek
      MYSQL_ROW_OFFSET mysql_row_tell(MYSQL_RES *result);
      //在结果集中移动当前位置，并返回之前的位置
      MYSQL_ROW_OFFSET mysql_row_seek(MYSQL_RES *result,MYSQL_ROW_OFFSET offset);
      //清理结果集
      void mysql_free_result(MYSQL_RES *result);

  • 5.处理返回的数据

    • //MySQL返回两种类型的数据，列数据和元数据
      
      //查询结果的基本信息，返回结果集中的字段（列）数目
      unsigned int mysql_field_count(MYSQL *connection);

  • Example

    • #include <stdlib.h>
      #include <stdio.h>
      
      #include "mysql.h"
      
      MYSQL my_connection;
      MYSQL_RES *res_ptr;
      MYSQL_ROW sqlrow;
      
      void display_row()
      {
          unsigned int field_count;
          field_count = 0;
          while(field_count < mysql_field_count(&my_connection))
          {
              printf("%s ",sqlrow[field_count]);
              field_count++;
          }
          printf("
      ");
      }
      int main(int argc, char *argv[])
      {
          int res;
          
          mysql_init(&my_connection);
          if(mysql_real_connect(&my_connection,"localhost","rick","secret","foo",0,NULL,0))
          {
              printf("Connection success
      ");
              res = mysql_query(&my_connection,"select childno, fname,age from children where age > 5");
              if(res)
              {
                  printf("select error:%s
      ",mysql_error(&my_connection));
              }
              else
              {
                  res_ptr = mysql_store_result(&my_connection);
                  if(res_ptr)
                  {
                      printf("Retrieved %lu rows
      ",(unsigned long)mysql_num_rows(res_ptr));
                      while((sqlrow = mysql_fetch_row(res_ptr)))
                      {
                          printf("Fetched data...
      ");
                          display_row();
                      }
                      if(mysql_errno(&my_connection))
                      {
                          fprintf(stderr,"Retrive error:%s
      ",mysql_error(&my_connection));
                      }
                      mysql_free_result(res_ptr);
                  }
              }
              mysql_close(&my_connection);
          }
          else
          {
              fprintf(stderr,"Connection failed
      ");
              if(mysql_errno(&my_connection))
              {
                  fprintf(stderr,"Connection error %d:%s
      ",mysql_error(&my_connection));
              }
          }
          return EXIT_SUCCESS;
      }

      • 编译：
        • 　首先查看mysql.h的安装位置
          • locate  mysql.h
          • g++ main.cpp  MysqlHelper.cpp -I /usr/local/mysql/include/ -L /usr/local/mysql/lib/ -lmysqlclient