From 48b649516e8077880690bc6873b48611e1a03513 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Sat, 11 Jul 2026 19:26:49 +0200
Subject: CRUD Operationen

---
 src/db-test.c | 156 ++++++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 108 insertions(+), 48 deletions(-)

(limited to 'src')

diff --git a/src/db-test.c b/src/db-test.c
index 439ed79..1538702 100644
--- a/src/db-test.c
+++ b/src/db-test.c
@@ -1,9 +1,13 @@
+#include <fcntl.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <limits.h>
+#include <string.h>
 
+// Berkeley DB 1.85
 #include <db.h>
-#include <fcntl.h>
+
+#define MODE 0600
 
 #define USERNAME_LENGTH 20
 #define FULLNAME_LENGTH 50
@@ -11,60 +15,116 @@
 typedef struct {
 	char username[USERNAME_LENGTH];
 	char fullname[FULLNAME_LENGTH];
-	int age;
+	int  age;
 } user_type;
 
-int main(void)
+void
+insert(DB *database)
 {
-	DB *db = dbopen("./database.db", O_RDWR | O_CREAT, 0644, DB_BTREE, NULL); // NOLINT
-	if ( db != NULL ) {
-		(void) fprintf(stderr, "Datenbank eröffnet...\n");
-
-#if INSERT
-		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 = sizeof(users[i].username) };
-
-			int res = db->put(db, &key, &data, 0);
-			if ( res == -1 ) {
-				fprintf(stderr, "failed to insert data!\n");
-			}
-		}
-#endif
-
-#if LOOKUP
-		{
-			DBT key = { .data = &users[0].username, .size = sizeof(users[0].username) };
-			DBT data;
-
-			int res = db->get(db, &key, &data, 0);
-			if ( res == 0 ) {
-				user_type *user = data.data;
-				printf("Fullname: %s, Age: %d\n", user->fullname, user->age);
-			}
+	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 res = database->put(database, &key, &data, 0);
+		if ( res == -1 ) {
+			(void) fprintf(stderr, "failed to insert data!\n");
 		}
-#endif
+	}
+}
 
-		{
-			DBT key;
-			DBT data;
+void
+update(DB *database, const char *username, int new_age)
+{
+	DBT key = { .data = (void *) username, .size = strlen(username) };
+	DBT old_data;
 
-			int err = db->seq(db, &key, &data, R_FIRST);
-			while ( !err ) {
-				user_type *user = data.data;
-				printf("Fullname: %s, Age: %d\n", user->fullname, user->age);
+	int res = database->get(database, &key, &old_data, 0);
+	if ( res != 0 ) {
+		(void) fprintf(stderr, "update: Datensatz %s nicht gefunden!\n", username);
+		return;
+	}
 
-				err = db->seq(db, &key, &data, R_NEXT);
-			}
-		}
+	// update
+	user_type user;
+	memcpy(&user, old_data.data, sizeof user);
+	user.age = new_age;
+
+	DBT new_data = {
+		.data = &user,
+		.size = sizeof user
+	};
+
+	res = database->put(database, &key, &new_data, 0);
+
+	if ( res != 0 ) {
+		(void) fprintf(stderr, "update: Datensatz %s wurde nicht aktualisiert\n", username);
+	}
+}
+
+void delete(DB *database, const char *username)
+{
+	DBT key = { .data = (void *) username, .size = strlen(username) };
+
+	int res = database->del(database, &key, 0);
+	if ( res != 0 ) {
+		(void) fprintf(stderr, "update: Datensatz %s wurde nicht gelöscht\n", username);
+	}
+}
+
+void
+lookup(DB *database, const char *username)
+{
+	DBT key = { .data = (void *) username, .size = strlen(username) };
+	DBT data;
 
-		db->close(db);
+	int res = database->get(database, &key, &data, 0);
+	if ( res == 0 ) {
+		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 err = database->seq(database, &key, &data, R_FIRST);
+	while ( !err ) {
+		user_type *user = data.data;
+		printf("%.*s -> %s (%d)\n", (int) key.size, (char *) key.data, user->fullname, user->age);
+
+		err = database->seq(database, &key, &data, R_NEXT);
+	}
+}
+
+int
+main(void)
+{
+	DB *database = dbopen("./database.db", 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");
+
+	delete(database, "user1");
+
+	update(database, "datengott", 50);
+
+	list(database);
+
+	database->close(database);
+
 	return EXIT_SUCCESS;
 }
-- 
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