MySQL入門之一次函數調用執行多條語句

 支持在單個字符串中指定的多語句的執行。要想與給定的鏈接一塊兒使用該功能，打開鏈接時，必須將標誌參數中的CLIENT_MULTI_STATEMENTS選項指定給mysql_real_connect()。也能夠經過調用mysql_set_server_option(MYSQL_OPTION_MULTI_STATEMENTS_ON)，爲已有的鏈接設置它。

經常使用套路：

/* Connect to server with option CLIENT_MULTI_STATEMENTS */
mysql_real_connect(..., CLIENT_MULTI_STATEMENTS);

/* Now execute multiple queries */
mysql_query(mysql,"DROP TABLE IF EXISTS test_table;\ CREATE TABLE test_table(id INT);\ INSERT INTO test_table VALUES(10);\ UPDATE test_table SET id=20 WHERE id=10;\ SELECT * FROM test_table;\ DROP TABLE test_table");
do
{
  /* Process all results */
  ...
  printf("total affected rows: %lld", mysql_affected_rows(mysql));
  ...
  if (!(result= mysql_store_result(mysql)))
  {
     printf(stderr, "Got fatal error processing query\n");
     exit(1);
  }
  process_result_set(result); /* client function */
  mysql_free_result(result);
} while (!mysql_next_result(mysql));

具體看代碼：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dlfcn.h>
#include <mysql/mysql.h>

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <termios.h>
#include <mysql/mysql.h>

void process_result_set(MYSQL       *mysql, MYSQL_RES *result)
{
        int i =0;
        unsigned int fieldnum;
        //從結果集，獲取表頭信息
        MYSQL_FIELD *fields = mysql_fetch_fields(result);
        fieldnum = mysql_field_count(mysql);
        for (i=0; i<fieldnum; i++)
        {
            printf("%s\t", fields[i].name);
        }
        printf("\n");


        //從結果集， 按照行獲取信息信息
        MYSQL_ROW row = NULL;
        //從結果集中一行一行的獲取數據
        while (  row = mysql_fetch_row(result))
        {
            fieldnum = mysql_field_count(mysql); 
            //優化，個人行有多少列。。。。查找這樣的api函數
            for (i=0; i<fieldnum; i++) //通過測試 發現 不是以0結尾的指針數組。。
            {
                printf("%s\t", row[i]);
            }
            printf("\n");
        }
}
int main()
{
    int         ret = 0, status = 0;

    MYSQL       *mysql;

    MYSQL_RES   *result;
    MYSQL_ROW   row;
    char        *query;


    mysql = mysql_init(NULL);

    mysql =mysql_real_connect(mysql, "localhost", "root", "123456", "mydb2", 0, NULL, CLIENT_MULTI_STATEMENTS);
    if (mysql == NULL)
    {
        ret = mysql_errno(mysql);
        printf("func mysql_real_connect() err\n");
        return ret;
    }
    else
    {
        printf(" ok......\n");
    }

    /* execute multiple statements */
status = mysql_query(mysql,
"DROP TABLE IF EXISTS test_table;\ CREATE TABLE test_table(id INT);\ INSERT INTO test_table VALUES(10);\ UPDATE test_table SET id=20 WHERE id=10;\ SELECT * FROM test_table;\ DROP TABLE test_table");
    if (status)
    {
        printf("Could not execute statement(s)");
        mysql_close(mysql);
        exit(0);
    }
    /* process each statement result */
    do {
            /* did current statement return data? */
            result = mysql_store_result(mysql);
            if (result)
            {
                /* yes; process rows and free the result set */

                process_result_set(mysql, result);

                mysql_free_result(result);
            }
            else /* no result set or error */
            {
                if (mysql_field_count(mysql) == 0)
                {
                    printf("%lld rows affected\n",
                    mysql_affected_rows(mysql));
                }
                else /* some error occurred */
                {
                    printf("Could not retrieve result set\n");
                    break;
                }
            }
        /* more results? -1 = no, >0 = error, 0 = yes (keep looping) */
        if ((status = mysql_next_result(mysql)) > 0)
                printf("Could not execute statement\n");
    } while (status == 0);

    mysql_close(mysql);

}