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#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// Berkeley DB 1.85
#include <db.h>
#define DATABASE_NAME "./database.db"
#define MODE 0600
#define USERNAME_LENGTH 20
#define FULLNAME_LENGTH 50
typedef struct {
char username[USERNAME_LENGTH];
char fullname[FULLNAME_LENGTH];
int age;
} user_type;
void
insert(DB *database)
{
user_type users[] = {
{ "datengott", "Thomas Schmucker", 44 },
{ "user1", "Sabine Müller", 23 },
{ "sql-user", "SQL Database User", -1 }
};
for ( int i = 0; i != 3; ++i ) {
DBT data = { .data = &users[i], .size = sizeof(users[i]) };
DBT key = { .data = users[i].username, .size = strlen(users[i].username) };
int error = database->put(database, &key, &data, 0);
if ( error ) {
(void) fprintf(stderr, "Datensatz konnte nicht eingefügt werden!\n");
}
}
}
void
update(DB *database, const char *username, int new_age)
{
DBT key = { .data = (void *) username, .size = strlen(username) };
DBT old_data;
int error = database->get(database, &key, &old_data, 0);
if ( error ) {
(void) fprintf(stderr, "Datensatz %s nicht gefunden!\n", username);
return;
}
// update
user_type user;
memcpy(&user, old_data.data, sizeof user);
user.age = new_age;
DBT new_data = {
.data = &user,
.size = sizeof user
};
error = database->put(database, &key, &new_data, 0);
if ( error ) {
(void) fprintf(stderr, "Datensatz %s wurde nicht aktualisiert\n", username);
}
}
void
erase(DB *database, const char *username)
{
DBT key = { .data = (void *) username, .size = strlen(username) };
int error = database->del(database, &key, 0);
if ( error ) {
(void) fprintf(stderr, "Datensatz %s wurde nicht gelöscht\n", username);
}
}
void
lookup(DB *database, const char *username)
{
DBT key = { .data = (void *) username, .size = strlen(username) };
DBT data;
int error = database->get(database, &key, &data, 0);
if ( !error ) {
user_type *user = data.data;
printf("%.*s -> %s (%d)\n", (int) key.size, (char *) key.data, user->fullname, user->age);
}
}
void
list(DB *database)
{
DBT key;
DBT data;
int error = database->seq(database, &key, &data, R_FIRST);
while ( !error ) {
user_type *user = data.data;
printf("%.*s -> %s (%d)\n", (int) key.size, (char *) key.data, user->fullname, user->age);
error = database->seq(database, &key, &data, R_NEXT);
}
}
int
main(void)
{
DB *database = dbopen(DATABASE_NAME, O_RDWR | O_CREAT, MODE, DB_BTREE, NULL);
if ( database == NULL ) {
(void) fprintf(stderr, "Datenbank konnte nicht geöffnet werden\n");
return EXIT_FAILURE;
}
insert(database);
lookup(database, "user1");
erase(database, "user1");
update(database, "datengott", 50);
list(database);
database->close(database);
return EXIT_SUCCESS;
}
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