diff --git a/CMakeLists.txt b/CMakeLists.txt
index c53101c..4d9f0a1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,14 +10,13 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 if(MSVC)
   add_compile_options(/W4 /WX)
 else()
-  add_compile_options(-Wall -Wpedantic)
+  add_compile_options(-W -Wall -Werror)
 endif()
 
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
 set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
 
-include(CTest)
 enable_testing()
 
 add_subdirectory(src)
diff --git a/src/core/article.cpp b/src/core/article.cpp
index 3270da7..4ba0b33 100644
--- a/src/core/article.cpp
+++ b/src/core/article.cpp
@@ -1,17 +1,24 @@
 #include "article.h"
 
-Article::Article() : Entity() {}
+Article::Article() : Entity()
+{}
 
-Article::Article(std::shared_ptr<Seller> sellerPtr) : Entity() { sellerPtr_ = sellerPtr; }
+Article::Article(const std::shared_ptr<Seller> sellerPtr) : Entity()
+{
+    this->sellerPtr = sellerPtr;
+}
 
-void Article::setArticleNo(int articleNo) { articleNo_ = articleNo; }
+void Article::setArticleNo(int articleNo)
+{
+    this->articleNo = articleNo;
+}
 
-void Article::setPrice(int price) { price_ = price; }
+void Article::setPrice(int price)
+{
+    this->price = price;
+}
 
-void Article::setDescription(const std::string& description) { description_ = description; }
-
-std::string Article::getDescription() { return description_; }
-
-void Article::setSale(std::shared_ptr<Sale> salePtr) { salePtr_ = salePtr; }
-
-bool Article::isSold() { return salePtr_ ? true : false; }
\ No newline at end of file
+void Article::setDescription(const std::string& description)
+{
+    this->description = description;
+}
\ No newline at end of file
diff --git a/src/core/article.h b/src/core/article.h
index 1d0487b..cc25ffa 100644
--- a/src/core/article.h
+++ b/src/core/article.h
@@ -2,33 +2,26 @@
 #define ARTICLE_H
 
 #include "entity.h"
-#include "sale.h"
 #include "seller.h"
 
-#include <memory>
 #include <string>
+#include <memory>
 
 class Seller;
 
 class Article : public Entity
 {
-  public:
+public:
     Article();
     Article(std::shared_ptr<Seller> sellerPtr);
     void setArticleNo(int articleNo);
     void setPrice(int price);
     void setDescription(const std::string& description);
-    std::string getDescription();
-    bool isSold();
-    void setSale(std::shared_ptr<Sale> salePtr);
-    void setSeller(std::shared_ptr<Seller> sellerPtr);
-
-  private:
-    std::shared_ptr<Seller> sellerPtr_{};
-    std::shared_ptr<Sale> salePtr_{};
-    int articleNo_{};
-    int price_{};
-    std::string description_{};
+private:
+    std::shared_ptr<Seller> sellerPtr{};
+    int articleNo{};
+    int price{};
+    std::string description{};
 };
 
 #endif
\ No newline at end of file
diff --git a/src/core/database.cpp b/src/core/database.cpp
index fc1a1c8..42603ad 100644
--- a/src/core/database.cpp
+++ b/src/core/database.cpp
@@ -2,40 +2,28 @@
 
 #include <iostream>
 #include <stdexcept>
-#include <vector>
 
 Database::Database(const std::string& dbname) : db_(nullptr)
 {
-    dbname_ = dbname;
-    const int errCode = sqlite3_open(dbname_.c_str(), &db_);
+    const int errCode = sqlite3_open(dbname.c_str(), &db_);
     if (errCode) {
         throw std::runtime_error("Could not open database file.");
     }
-    sqlite3_db_config(db_, SQLITE_DBCONFIG_ENABLE_FKEY);
+    exec("PRAGMA foreign_key = 1");
 }
 
 Database::~Database() { sqlite3_close(db_); }
 
 void Database::exec(const std::string& sql)
 {
-    char* errMsg;
-    const int errCode = sqlite3_exec(db_, sql.c_str(), nullptr, nullptr, &errMsg);
+    const int errCode = sqlite3_exec(db_, sql.c_str(), nullptr, nullptr, nullptr);
     if (errCode) {
-        std::string errMsgString(errMsg); // Make a C++ string of the errMsg, so that we can call
-                                          // sqlite3_free() before throwing the exception
-        sqlite3_free(errMsg);
-        throw std::runtime_error("Error in SQL execution: " + errMsgString);
+        throw std::runtime_error("Error in SQL execution.");
     }
 }
 
-void Database::createNew()
+void Database::init()
 {
-    std::vector<std::string> sqlStrings{};
-
-    std::string sqlCreateKima2{"CREATE TABLE IF NOT EXISTS kima2 ("
-                               "version INTEGER NOT NULL);"
-                               "INSERT INTO kima2 (version) VALUES (1);"};
-    sqlStrings.push_back(sqlCreateKima2);
     std::string sqlCreateSellers{"CREATE TABLE IF NOT EXISTS sellers ("
                                  "id TEXT PRIMARY KEY NOT NULL, "
                                  "seller_no INTEGER, "
@@ -44,7 +32,7 @@ void Database::createNew()
                                  "offered_articles INTEGER, "
                                  "UNIQUE (seller_no)"
                                  ");"};
-    sqlStrings.push_back(sqlCreateSellers);
+
     std::string sqlCreateArticles{
         "CREATE TABLE IF NOT EXISTS articles ("
         "id TEXT PRIMARY KEY NOT NULL, "
@@ -57,90 +45,13 @@ void Database::createNew()
         "FOREIGN KEY (seller_id) REFERENCES sellers(id) ON DELETE CASCADE, "
         "CHECK (article_no BETWEEN 0 AND 99999)"
         ");"};
-    sqlStrings.push_back(sqlCreateArticles);
-    std::string sqlCreateSales{"CREATE TABLE IF NOT EXISTS sales ("
-                               " id TEXT PRIMARY KEY NOT NULL,"
-                               " source_no INTEGER NOT NULL,"
-                               " sold_at TEXT"
-                               ");"};
-    sqlStrings.push_back(sqlCreateSales);
-    std::string sqlCreateSalesItems{
-        "CREATE TABLE IF NOT EXISTS sales_items("
-        " sale_id TEXT NOT NULL,"
-        " article_id TEXT NOT NULL,"
-        " FOREIGN KEY (sale_id) REFERENCES sales(id) ON DELETE CASCADE,"
-        " FOREIGN KEY (article_id) REFERENCES articles(id) ON DELETE CASCADE"
-        ");"};
-    sqlStrings.push_back(sqlCreateSalesItems);
 
     beginTransaction();
-    for (const auto& sql : sqlStrings) {
-        exec(sql);
-    }
+    exec(sqlCreateSellers);
+    exec(sqlCreateArticles);
     endTransaction();
 }
 
-void Database::init()
-{
-    int version = getVersion();
-
-    switch (version) {
-    case 0:
-        createNew();
-        break;
-        // perhaps handle upgrades for db schema here...
-    default:
-        // Do nothing because we are up-to-date.
-        break;
-    }
-}
-
-int Database::getVersion()
-{
-    int retCode{};
-    sqlite3_stmt* stmt;
-
-    // Check if there's already a kima2 table available.
-    // If not, return version == 0.
-    retCode = sqlite3_prepare_v2(
-        db_, "SELECT count(*) FROM sqlite_master WHERE type='table' AND name='kima2';", -1, &stmt,
-        nullptr);
-    if (retCode != SQLITE_OK)
-        throw std::string(sqlite3_errmsg(db_));
-    retCode = sqlite3_step(stmt);
-    if (retCode != SQLITE_ROW && retCode != SQLITE_DONE) {
-        std::string errMsg(sqlite3_errmsg(db_));
-        sqlite3_finalize(stmt);
-        throw errMsg;
-    } else if (retCode != SQLITE_DONE) {
-        int count = sqlite3_column_int(stmt, 0);
-        sqlite3_finalize(stmt);
-        if (count == 0)
-            return 0; // no kima2 table, so version is 0
-    }
-
-    // Now that we know that the kima2 table is present, read and return the schema version.
-    retCode = sqlite3_prepare_v2(db_, "SELECT version FROM kima2", -1, &stmt, nullptr);
-    if (retCode != SQLITE_OK)
-        throw std::string(sqlite3_errmsg(db_));
-
-    retCode = sqlite3_step(stmt);
-
-    if (retCode != SQLITE_ROW && retCode != SQLITE_DONE) {
-        std::string errMsg(sqlite3_errmsg(db_));
-        sqlite3_finalize(stmt);
-        throw errMsg;
-    } else if (retCode == SQLITE_DONE) {
-        sqlite3_finalize(stmt);
-        return 0; // no version entry, so version is 0
-    }
-
-    int version = sqlite3_column_int(stmt, 0);
-    sqlite3_finalize(stmt);
-
-    return version;
-}
-
 void Database::beginTransaction() { exec("BEGIN TRANSACTION"); }
 
 void Database::endTransaction() { exec("END TRANSACTION"); }
\ No newline at end of file
diff --git a/src/core/database.h b/src/core/database.h
index ff6f3d8..c0b4de4 100644
--- a/src/core/database.h
+++ b/src/core/database.h
@@ -16,11 +16,8 @@ public:
     void init();
 private:
     sqlite3 *db_;
-    std::string dbname_;
     void beginTransaction();
     void endTransaction();
-    void createNew();
-    int getVersion();
 };
 
 #endif // DATABASE_H
\ No newline at end of file
diff --git a/src/core/sale.h b/src/core/sale.h
deleted file mode 100644
index 06f350d..0000000
--- a/src/core/sale.h
+++ /dev/null
@@ -1,8 +0,0 @@
-#ifndef SALE_H
-#define SALE_H
-
-class Sale : public Entity {
-
-};
-
-#endif
\ No newline at end of file
diff --git a/src/core/seller.cpp b/src/core/seller.cpp
index 634e585..e4de084 100644
--- a/src/core/seller.cpp
+++ b/src/core/seller.cpp
@@ -1,40 +1,26 @@
 #include "seller.h"
 
-Seller::Seller() : Entity() {}
+void Seller::setSellerNo(int seller_no)
+{
+    sellerNo_ = seller_no;
+}
 
-Seller::Seller(const std::string& firstName, const std::string& lastName, int sellerNo,
-               int numberOfArticles)
-    : Entity()
+void Seller::setFirstName(const std::string& firstName)
 {
     firstName_ = firstName;
-    lastName_ = lastName;
-    sellerNo_ = sellerNo;
-    numberOfOfferedArticles_ = numberOfArticles;
 }
 
-inline void Seller::setSellerNo(int seller_no) { sellerNo_ = seller_no; }
-
-inline void Seller::setFirstName(const std::string& firstName) { firstName_ = firstName; }
-
-inline void Seller::setLastName(const std::string& lastName) { lastName_ = lastName; }
-
-inline void Seller::setNumberOfOfferedArticles(int number) { numberOfOfferedArticles_ = number; }
-
-inline size_t Seller::getNumberOfOfferedArticles() { return articles_.size(); }
-
-void Seller::addArticle(Article article) {
-    articles_.push_back(article);
-}
-
-std::vector<Article*> Seller::getArticles(bool onlySold)
+void Seller::setLastName(const std::string& lastName)
 {
-    std::vector<Article*> articles;
-    for (auto& article : articles_) {
-        if (onlySold && article.isSold()) {
-            articles.push_back(&article);
-        } else if (!onlySold) {
-            articles.push_back(&article);
-        }
-    }
-    return articles;
+    lastName_ = lastName;
+}
+
+void Seller::setNumberOfOfferedArticles(int number)
+{
+    numberOfOfferedArticles_ = number;
+}
+
+size_t Seller::getNumberOfOfferedArticles()
+{
+    return articles_.size();
 }
\ No newline at end of file
diff --git a/src/core/seller.h b/src/core/seller.h
index 4ac6a98..2848579 100644
--- a/src/core/seller.h
+++ b/src/core/seller.h
@@ -1,8 +1,8 @@
 #ifndef SELLER_H
 #define SELLER_H
 
-#include "article.h"
 #include "entity.h"
+#include "article.h"
 
 #include <string>
 #include <vector>
@@ -12,17 +12,11 @@ class Article;
 class Seller : public Entity
 {
   public:
-    Seller();
-    Seller(const std::string& firstName, const std::string& lastName, int sellerNo = 0,
-           int numberOfArticles = 0);
-
     void setSellerNo(int sellerNo);
     void setFirstName(const std::string& firstName);
     void setLastName(const std::string& lastName);
     void setNumberOfOfferedArticles(int number);
-    void addArticle(Article article);
 
-    std::vector<Article*> getArticles(bool onlySold = false);
     size_t getNumberOfOfferedArticles();
 
   private:
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 382580f..2c68a6d 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -4,10 +4,6 @@ add_executable(test_seller test_seller.cpp)
 target_link_libraries(test_seller core Boost::unit_test_framework)
 add_test(NAME Seller COMMAND ${CMAKE_BINARY_DIR}/bin/test_seller)
 
-add_executable(test_article test_article.cpp)
-target_link_libraries(test_article core Boost::unit_test_framework)
-add_test(NAME Article COMMAND ${CMAKE_BINARY_DIR}/bin/test_article)
-
 add_executable(test_database test_database.cpp)
 target_link_libraries(test_database core Boost::unit_test_framework stdc++fs)
 add_test(NAME Database COMMAND ${CMAKE_BINARY_DIR}/bin/test_database)
diff --git a/test/test_article.cpp b/test/test_article.cpp
deleted file mode 100644
index e0792ad..0000000
--- a/test/test_article.cpp
+++ /dev/null
@@ -1,21 +0,0 @@
-#define BOOST_TEST_MODULE article
-
-#include "../src/core/article.h"
-
-#include <boost/test/included/unit_test.hpp>
-
-BOOST_AUTO_TEST_CASE(create_article)
-{
-    Article article{};
-    BOOST_TEST(article.getUuid().is_nil() == true);
-}
-
-BOOST_AUTO_TEST_CASE(check_is_sold)
-{
-    Article article{};
-    BOOST_TEST(article.isSold() == false);
-
-    auto salePtr = std::make_shared<Sale>();
-    article.setSale(salePtr);
-    BOOST_TEST(article.isSold() == true);
-}
\ No newline at end of file
diff --git a/test/test_database.cpp b/test/test_database.cpp
index de5c004..28d47dc 100644
--- a/test/test_database.cpp
+++ b/test/test_database.cpp
@@ -8,8 +8,18 @@
 
 BOOST_AUTO_TEST_CASE(create_database)
 {
+    std::filesystem::path testPath = std::filesystem::temp_directory_path() / "kima2test.db";
+    if (std::filesystem::exists(testPath)) {
+        std::filesystem::remove(testPath);
+    }
 
-    Database db(":memory:");
-    BOOST_CHECK_NO_THROW(db.init());
+    std::string filename = testPath.generic_string();
 
+    Database db(filename);
+    db.init();
+
+    BOOST_TEST(std::filesystem::exists(testPath) == true);
+    if (std::filesystem::exists(testPath)) {
+        std::filesystem::remove(testPath);
+    }
 }
\ No newline at end of file
diff --git a/test/test_seller.cpp b/test/test_seller.cpp
index 5de2ed2..d193340 100644
--- a/test/test_seller.cpp
+++ b/test/test_seller.cpp
@@ -2,37 +2,17 @@
 
 #include "../src/core/seller.h"
 
-#include <array>
-
 #include <boost/test/included/unit_test.hpp>
 
-BOOST_AUTO_TEST_CASE(create_uuid_nil)
-{
+//using namespace boost::unit_test;
+
+BOOST_AUTO_TEST_CASE( create_uuid_nil ) {
     Seller seller{};
     BOOST_TEST(seller.getUuid().is_nil() == true);
 }
 
-BOOST_AUTO_TEST_CASE(create_uuid)
-{
+BOOST_AUTO_TEST_CASE(create_uuid) {
     Seller seller{};
     seller.createUuid();
     BOOST_TEST(seller.getUuid().is_nil() == false);
-}
-
-BOOST_AUTO_TEST_CASE(create_many)
-{
-    constexpr unsigned int QUANTITY{10000};
-    std::array<Seller, QUANTITY> sellers;
-    for (unsigned i = 0; i < sellers.size(); i++) {
-        sellers[i] = Seller();
-        sellers[i].createUuid();
-    }
-}
-
-BOOST_AUTO_TEST_CASE(with_article) {
-    Seller seller("Max", "Mustermann");
-    Article article{};
-    article.setDescription("Test article");
-    seller.addArticle(article);
-    BOOST_TEST(seller.getArticles().at(0)->getDescription() == "Test article");
 }
\ No newline at end of file