Linux C 数据库编程

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初学数据库

#include <stdio.h>
#include <stdlib.h>
#include <sqlite3.h>

int create_table(sqlite3 *db)
{
char *errmsg = NULL;
char *sql;

sql = "create table if not exists mytable (id integer primary key,name text);";

if(SQLITE_OK != sqlite3_exec (db,sql,NULL,NULL,&errmsg))
{
printf("operator fail:%s\n",errmsg);
exit(0);
}
}

int displaycd(void *para,int column_count ,char ** column_value, char ** column_name)
{
int i;

printf("total column is %d\n",column_count);

for(i = 0; i < column_count; i++)
{
printf("column_name: %s->column_value: %s\n",column_name[i],column_value[i]);

}

printf("*****************************\n");

return 0;
}

int inquire_usecd(sqlite3 *db)
{
char *errmsg = NULL;
char *sql;

sql = "select * from mytable;";

if(SQLITE_OK != sqlite3_exec(db,sql,displaycd,NULL,&errmsg))
{
printf("operator failed:%s\n",errmsg);
exit(-1);
}

}

int delete_record(sqlite3 *db)
{
char sql[100];
char *errmsg;
int id;

printf("please a id to be deleted:\n");
scanf("%d",&id);

sprintf(sql ,"delete from mytable where id = %d;",id);

if(SQLITE_OK != sqlite3_exec(db,sql,NULL,NULL,&errmsg))
{
  printf("operator fail:%s\n",errmsg);
  exit(-1);
}

}

int insert_record(sqlite3 *db)
{

char sql[100];
char *errmsg;
int id;
int i;
char name[100];

printf("please insert id,name \n");
scanf("%d%s",&id,name);

sprintf(sql ,"insert into mytable (id,name) values (%d,'%s');",id,name);

if(SQLITE_OK != sqlite3_exec(db,sql,NULL,NULL,&errmsg))
{
  printf("operator fail:%s\n",errmsg);
}

}

int inquire_nocb(sqlite3 *db)
{
int nrow,ncolumn;
char **azresult;
char *sql;
char * errmsg;
int i;

sql = "select * from mytable;";

if(SQLITE_OK != sqlite3_get_table(db,sql,&azresult,&nrow,&ncolumn,&errmsg))
{
printf("operator failed: %s\n",errmsg);
exit(0);
}

printf("row:%d column: %d\n",nrow,ncolumn);
printf("the result of querying is:\n");

for(i = 0; i < (nrow + 1) *ncolumn; i++)
{
  printf("%10s",azresult[i]);
  if((i + 1) % ncolumn == 0)
  {
   printf("\n");
  }
}

sqlite3_free_table(azresult);
}

int main()
{
sqlite3 *db = NULL;
int ret;
ret = sqlite3_open("mydatabase.db",&db);
if(ret != SQLITE_OK)
{
  perror("sqlite open");
  exit(-1);
}

else

{
  printf("you have opened a sqlite3!\n");
}

create_table(db);
insert_record(db);
inquire_usecd(db);
    //delete_record(db);
    inquire_usecd(db);
    inquire_nocb(db);
    return 0;
}

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