Reading Sensor in c

#include <my_global.h>
#include <mysql.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#define MAX_BUF 50

unsigned short Adc_read(unsigned int pin)
{
  int fd,rval;
  char buf[MAX_BUF];
  char val[5]={0};

  sprintf(buf,"/sys/devices/ocp.2/helper.14/AIN%d", pin);

  fd = open(buf, O_RDONLY);
  if (fd < 0)
  {
    printf("unable to open the ADC device ");
    exit(1);
  }

  rval=read(fd, &val, sizeof val);

  if(rval<=0)
  {
    perror("read");
    //close(fd);
    //exit(1);

  }

  close(fd);

  return (unsigned short)atoi(val);



}

int main(int argc,char *argv[])
{
   unsigned short Temp_Val,Humid_Val;
   unsigned int Temp_pin,Humid_pin;
   float temp,Rest,Rhumid;
   char query[100]={0};

/* read the pin numbers from the Command line arguments */

   if(argc!=3)
   {
     printf("Usage ./readsensor <temppin1> <humidpin2> \n");
     exit(1);
   }

    Temp_pin=atoi(argv[1]);
    Humid_pin=atoi(argv[2]);

   if((Temp_pin < 0 || Temp_pin >6 ) ||  (Humid_pin < 0 || Humid_pin > 6))
   {
      printf("Enter the ADC pin numbers between 0 and 6  \n ");
      exit(1);
   }

 /* create an MYSQL object */

   MYSQL *con = mysql_init(NULL);

   if (con == NULL)
   {
      fprintf(stderr, "%s\n", mysql_error(con));
      exit(1);
   }

   /* connect to the MYSQL database */

   if(mysql_real_connect(con,"localhost","sanpai","sanpai",0,0,0,0)==NULL)
   {
     fprintf(stderr, "%s\n", mysql_error(con));
     mysql_close(con);
     exit(1);
   }

/* Select the database */

  if(mysql_select_db(con,"TempDB")!=0)
  {
    fprintf(stderr,"%s \n",mysql_error(con));
    mysql_close(con);
    exit(1);
  }

   while(1)
   {
     // printf("Temppin = %d \n",Temp_pin);
     // printf("Humidpin = %d \n",Humid_pin);
     Temp_Val=Adc_read(Temp_pin);
     Humid_Val=Adc_read(Humid_pin);
     Humid_Val=Humid_Val*3/1000;

     printf("Temp_Val = %hd \n",Temp_Val);
     printf("Humid_Val = %hd \n",Humid_Val);

     if(Humid_Val!=0)
     {
       Rest=((5-Humid_Val)/Humid_Val)*3000;
       Rhumid=-9.371*log(Rest)+157.91;
     }
     else
     {


     }

      temp= ((float)Temp_Val)/10;


      printf("The temperature value is = %f C \n",temp);
      printf("The Humidity  is = %f %% \n",Rhumid);
     // printf("Temp val = %hd \n",Temp_Val);
      //printf("Humid val = %hd \n",Humid_Val);

      memset(query,0,sizeof query);

      sprintf(query,"UPDATE Datavalues SET Temperature = %f,Humidity = %f,Date=NOW() WHERE Rownum=0",temp,Rhumid);

      if (mysql_query(con,query))
      {
         fprintf(stderr, "%s\n", mysql_error(con));
         mysql_close(con);
         exit(1);
      }


      usleep(1000000);
      temp=0;
      Rhumid=0;
   }

  mysql_close(con);
  return 0;
}