diff --git a/server/db/database.js b/server/db/database.js
index 693f083..5d11592 100644
--- a/server/db/database.js
+++ b/server/db/database.js
@@ -24,7 +24,7 @@ export default class DBAdapter {
     #dbName = 'N';
     #dbUserLogin = 'u';
     #dbUserPassword = 'p';
-    #dbClient = null;
+    #pool = null;
 
     constructor({
         dbHost,
@@ -38,40 +38,43 @@ export default class DBAdapter {
         this.#dbName = dbName;
         this.#dbUserLogin = dbUserLogin;
         this.#dbUserPassword = dbUserPassword;
-        this.#dbClient = new mdb.createPool({
+        this.#pool = mdb.createPool({
             host: this.#dbhost,
             port: this.#dbPort,
             database: this.#dbName,
             user: this.#dbUserLogin,
             password: this.#dbUserPassword,
-            dateStrings: true
+            dateStrings: true,
+            acquireTimeout: 10000,
         });
     }
 
+    async #getConnection() {
+        return await this.#pool.getConnection();
+    }
+    
     async connect() {
         try {
-            // Проверяем подключение, выполняя простой запрос
-            const conn = await this.#dbClient.getConnection();
+            const conn = await this.#pool.getConnection();
             console.log("✅ Database connection test successful");
             conn.release();
         } catch (err) {
             console.error("❌ Database connection failed:", err.message);
-            // Пробрасываем ошибку дальше
             return Promise.reject();
         }
     }
 
     async disconnect() {
-        await this.#dbClient.end();
+        await this.#pool.end();
         console.log("DISCONNECT");
     }
 
     async stock(){
         try {
-            const products = await this.#dbClient.query('SELECT id FROM products');
+            const products = await this.#pool.query('SELECT id FROM products');
             for (const product of products) {
                 const increment = Random_Increase();
-                await this.#dbClient.query('UPDATE products SET quantity = quantity + ? WHERE id = ?', [
+                await this.#pool.query('UPDATE products SET quantity = quantity + ? WHERE id = ?', [
                     increment,
                     product.id
                 ]);
@@ -86,8 +89,7 @@ export default class DBAdapter {
 
     async getProducts() {
         try {
-            const products = await this.#dbClient.query('SELECT * FROM products ORDER BY name');
-            console.log("All products:", products);
+            const products = await this.#pool.query('SELECT * FROM products ORDER BY name');
             return products;
         } catch(err){
             console.log(`WHOOPS`);
@@ -97,14 +99,12 @@ export default class DBAdapter {
 
     async getOrders() {
         try {
-            const raw_orders = await this.#dbClient.query('SELECT * FROM orders ORDER BY order_date ASC');
-            console.log("All orders:", raw_orders);
+            const raw_orders = await this.#pool.query('SELECT * FROM orders ORDER BY order_date ASC');
             
-            const items = await this.#dbClient.query(
+            const items = await this.#pool.query(
                 `SELECT order_items.*, products.name AS product_name FROM order_items
                 JOIN products ON order_items.product_id = products.id`
             );
-            console.log("All order items:", items);
             
             const groupedItems = {};
             if (items && items.length > 0) {
@@ -132,7 +132,7 @@ export default class DBAdapter {
     }
 
     async addOrder({ id, customer_name, orderDate} ){
-        if (!customer_name || !orderDate){
+        if (!id || !customer_name || !orderDate){
             return Promise.reject({
                 type: DB_USER_ERROR,
                 error: new Error("Empty in customer name or order date")
@@ -146,7 +146,7 @@ export default class DBAdapter {
             });
         }
         try {
-            await this.#dbClient.query('INSERT INTO orders (id, customer_name, order_date) VALUES (?, ?, ?)',
+            await this.#pool.query('INSERT INTO orders (id, customer_name, order_date) VALUES (?, ?, ?)',
                 [id, customer_name, orderDate]
             );
         } catch(err){
@@ -159,7 +159,7 @@ export default class DBAdapter {
 
     async getOrdersByDate(date){
         try {
-            const order_ids = await this.#dbClient.query('SELECT id FROM orders WHERE order_date = ?', [date]);
+            const order_ids = await this.#pool.query('SELECT id FROM orders WHERE order_date = ?', [date]);
             return order_ids;
         } catch(err){
             return Promise.reject();
@@ -175,7 +175,7 @@ export default class DBAdapter {
         try {
             const placeholders = orderIds.map(() => '?').join(',');
             
-            const result = await this.#dbClient.query(
+            const result = await this.#pool.query(
                 `DELETE FROM orders WHERE id IN (${placeholders})`,
                 orderIds
             );
@@ -188,11 +188,12 @@ export default class DBAdapter {
         }
     }
 
-    async changeOrderInfo({ id, customer_name, orderDate }){
-        if (!id) {
+    async changeOrderInfo({ id, customer_name, orderDate }) {
+        if (!id || !customer_name || !orderDate) {
             return Promise.reject({
                 type: DB_USER_ERROR,
-                error: new Error("Order ID is required")
+                error: new Error("Order ID, name or date is required!"),
+                message: "Order ID, name or date is required!" // Добавляем message напрямую
             });
         }
 
@@ -200,100 +201,205 @@ export default class DBAdapter {
         if (orderDate < currentDate) {
             return Promise.reject({
                 type: DB_USER_ERROR,
-                error: new Error("Order date cannot be less than current date")
+                error: new Error("Order date cannot be less than current date"),
+                message: "Order date cannot be less than current date"
             });
         }
 
         try {
-            const order = await this.#dbClient.query('SELECT * FROM orders WHERE id = ?', [id]);
+            const order = await this.#pool.query('SELECT * FROM orders WHERE id = ?', [id]);
 
-            if (!order){
+            if (!order || order.length === 0) { // Исправлено: проверяем length
                 return Promise.reject({
                     type: DB_USER_ERROR,
-                    error: new Error("Order not found")
+                    error: new Error("Order not found"),
+                    message: "Order not found"
                 });
             }
             
             const updatedName = customer_name;
             const updatedDate = orderDate;
 
-            await this.#dbClient.query('UPDATE orders SET customer_name = ?, order_date = ? WHERE id = ?',
+            await this.#pool.query('UPDATE orders SET customer_name = ?, order_date = ? WHERE id = ?',
                 [updatedName, updatedDate, id]
             );
 
-        } catch(err){
+        } catch(err) {
+            console.error('Database error in changeOrderInfo:', err);
             return Promise.reject({
                 type: DB_INTERNAL_ERROR,
-                error: new Error("Server error")
+                error: new Error("Server error"),
+                message: err.message || "Database operation failed",
+                details: err.message
             });
         }
     }
 
-    async deleteOrderById(order_id){
+    async deleteOrderById(order_id) {
+        let connection;
+        
         try {
-            const orderItems = await this.#dbClient.query(
+            connection = await this.#pool.getConnection();
+            await connection.beginTransaction();
+            
+            const orderItems = await connection.query(
                 `SELECT product_id, quantity FROM order_items WHERE order_id = ?`,
                 [order_id]
             );
 
-            for (const item of orderItems){
-                await this.#dbClient.query('UPDATE products SET quantity = quantity + ? WHERE id = ?', 
+            for (const item of orderItems) {
+                await connection.query(
+                    'UPDATE products SET quantity = quantity + ? WHERE id = ?', 
                     [item.quantity, item.product_id]
                 );
             }
-            await this.#dbClient.query(
+            
+            await connection.query(
+                `DELETE FROM order_items WHERE order_id = ?`,
+                [order_id]
+            );
+            
+            await connection.query(
                 `DELETE FROM orders WHERE id = ?`,
                 [order_id]
             );
-        } catch(err){
+
+            await connection.commit();
+            connection.release();
+            
+        } catch (err) {
+            if (connection) {
+                try {
+                    await connection.rollback();
+                } catch (rollbackErr) {
+                    console.error('Rollback error:', rollbackErr.message);
+                }
+                connection.release();
+            }
+            
             return Promise.reject({
                 type: DB_INTERNAL_ERROR,
-                error: new Error("Server error")
+                error: new Error("Failed to delete order"),
+                details: err.message
             });
         }
     }
 
-    async addOrderItem({ orderId, productId, quantity }){
-        await this.#dbClient.query('BEGIN');
+    async addOrderItem({ orderId, productId, quantity }) {
+        let connection;
+        
         try {
-            const product = await this.#dbClient.query(
-                'SELECT quantity FROM products WHERE id = ?', [productId]
+            connection = await this.#pool.getConnection();
+            
+            await connection.beginTransaction();
+            
+            const orderCheck = await connection.query(
+                'SELECT id FROM orders WHERE id = ?', 
+                [orderId]
+            );
+            
+            if (!orderCheck || orderCheck.length === 0) {
+                await connection.rollback();
+                connection.release();
+                return Promise.reject({
+                    type: DB_USER_ERROR,
+                    error: new Error("Order not found")
+                });
+            }
+            
+            const product = await connection.query(
+                'SELECT id, quantity FROM products WHERE id = ? FOR UPDATE', 
+                [productId]
             );
 
             const productRow = product?.[0];
-            if (!productRow || productRow.quantity < quantity){
+            
+            if (!productRow) {
+                await connection.rollback();
+                connection.release();
+                return Promise.reject({
+                    type: DB_USER_ERROR,
+                    error: new Error("Product not found")
+                });
+            }
+            
+            if (productRow.quantity < quantity) {
+                await connection.rollback();
+                connection.release();
                 return Promise.reject({
                     type: DB_USER_ERROR,
                     error: new Error("Insufficient product quantity")
                 });
             }
 
-            const result = await this.#dbClient.query(
-                'INSERT INTO order_items (order_id, product_id, quantity) VALUES (?, ?, ?)',
-                [orderId, productId, quantity]
-            );
-
-            await this.#dbClient.query(
+            await connection.query(
                 'UPDATE products SET quantity = quantity - ? WHERE id = ?',
                 [quantity, productId]
             );
 
-            await this.#dbClient.query('COMMIT');
-        } catch (err){
-            await this.#dbClient.query('ROLLBACK');
-            return Promise.reject();
+            const result = await connection.query(
+                'INSERT INTO order_items (order_id, product_id, quantity) VALUES (?, ?, ?)',
+                [orderId, productId, quantity]
+            );
+
+            await connection.commit();
+            
+            connection.release();
+            
+            return result.insertId;
+            
+        } catch (err) {
+            if (connection) {
+                try {
+                    await connection.rollback();
+                } catch (rollbackErr) {
+                    console.error('Rollback error:', rollbackErr.message);
+                }
+                connection.release();
+            }
+            
+            console.error('Transaction error:', err);
+            
+            let errorType = DB_INTERNAL_ERROR;
+            let userMessage = "Database operation failed";
+            let retryable = false;
+            
+            if (err.code === 'ER_LOCK_WAIT_TIMEOUT' || err.errno === 1205) {
+                errorType = 'DB_CONFLICT';
+                userMessage = "System is busy. Please try again in a moment.";
+                retryable = true;
+            } else if (err.code === 'ER_DUP_ENTRY') {
+                errorType = DB_USER_ERROR;
+                userMessage = "Item already exists in the order";
+            }
+            
+            return Promise.reject({
+                type: errorType,
+                error: new Error(userMessage),
+                details: err.message,
+                code: err.code,
+                retryable: retryable,
+                originalError: err
+            });
         }
     }
 
-    async updateOrderItem({ itemId, quantity }){
-        await this.#dbClient.query('BEGIN');
+    async updateOrderItem({ itemId, quantity }) {
+        let connection;
+        
         try {
-            const item = await this.#dbClient.query(
-                'SELECT product_id, quantity FROM order_items WHERE id = ?', [itemId]
+            connection = await this.#pool.getConnection();
+            await connection.beginTransaction();
+            
+            const item = await connection.query(
+                'SELECT product_id, quantity FROM order_items WHERE id = ? FOR UPDATE', 
+                [itemId]
             );
 
             const itemRow = item?.[0];
-            if (!itemRow){
+            if (!itemRow) {
+                await connection.rollback();
+                connection.release();
                 return Promise.reject({
                     type: DB_USER_ERROR,
                     error: new Error("Order item not found")
@@ -302,100 +408,177 @@ export default class DBAdapter {
 
             const diff = quantity - itemRow.quantity;
 
-            if (diff > 0){
-                const product = await this.#dbClient.query(
-                    'SELECT quantity FROM products WHERE id = ?', [itemRow.product_id]
+            if (diff > 0) {
+                const product = await connection.query(
+                    'SELECT quantity FROM products WHERE id = ? FOR UPDATE', 
+                    [itemRow.product_id]
                 );
 
                 const productRow = product?.[0];
-                if (!productRow || productRow.quantity < diff){
+                if (!productRow || productRow.quantity < diff) {
+                    await connection.rollback();
+                    connection.release();
                     return Promise.reject({
                         type: DB_USER_ERROR,
                         error: new Error("Insufficient product quantity")
                     });
                 }
                 
-                await this.#dbClient.query(
+                await connection.query(
                     'UPDATE products SET quantity = quantity - ? WHERE id = ?',
                     [diff, itemRow.product_id]
                 );
             }
 
             if (diff < 0) {
-                await this.#dbClient.query(
+                await connection.query(
                     'UPDATE products SET quantity = quantity + ? WHERE id = ?',
                     [-diff, itemRow.product_id]
                 );                
             }
 
-            await this.#dbClient.query(
+            await connection.query(
                 'UPDATE order_items SET quantity = ? WHERE id = ?',
                 [quantity, itemId]
-            );                
+            );
 
-            await this.#dbClient.query('COMMIT');
-        } catch (err){
-            await this.#dbClient.query('ROLLBACK');
-            return Promise.reject();
+            await connection.commit();
+            connection.release();
+            
+        } catch (err) {
+            if (connection) {
+                try {
+                    await connection.rollback();
+                } catch (rollbackErr) {
+                    console.error('Rollback error:', rollbackErr.message);
+                }
+                connection.release();
+            }
+            
+            return Promise.reject({
+                type: DB_INTERNAL_ERROR,
+                error: new Error("Failed to update order item"),
+                details: err.message
+            });
         }
     }
 
-    async deleteOrderItem(itemId){
-        await this.#dbClient.query('BEGIN');
+    async deleteOrderItem(itemId) {
+        let connection;
+        
         try {
-            const item = await this.#dbClient.query(
-                'SELECT product_id, quantity FROM order_items WHERE id = ?', [itemId]
+            connection = await this.#pool.getConnection();
+            await connection.beginTransaction();
+            
+            const item = await connection.query(
+                'SELECT product_id, quantity FROM order_items WHERE id = ? FOR UPDATE', 
+                [itemId]
             );
 
             const itemRow = item?.[0];
-            if (!itemRow){
+            if (!itemRow) {
+                await connection.rollback();
+                connection.release();
                 return Promise.reject({
                     type: DB_USER_ERROR,
                     error: new Error("Order item not found")
                 });
             }
 
-            await this.#dbClient.query(
+            await connection.query(
                 'UPDATE products SET quantity = quantity + ? WHERE id = ?',
                 [itemRow.quantity, itemRow.product_id]
             );
 
-            await this.#dbClient.query(
+            await connection.query(
                 'DELETE FROM order_items WHERE id = ?',
                 [itemId]
             );
 
-            await this.#dbClient.query('COMMIT');
-        } catch (err){
-            await this.#dbClient.query('ROLLBACK');
-            return Promise.reject();
+            await connection.commit();
+            connection.release();
+            
+        } catch (err) {
+            if (connection) {
+                try {
+                    await connection.rollback();
+                } catch (rollbackErr) {
+                    console.error('Rollback error:', rollbackErr.message);
+                }
+                connection.release();
+            }
+            
+            console.error('Delete order item error:', err);
+            
+            return Promise.reject({
+                type: DB_INTERNAL_ERROR,
+                error: new Error("Failed to delete order item"),
+                details: err.message,
+                itemId: itemId
+            });
         }
     }
 
-    async moveOrderItem( {itemId, targetOrderId }){
-        await this.#dbClient.query('BEGIN');
+    async moveOrderItem({ itemId, targetOrderId }) {
+        let connection;
+        
         try {
-            const item = await this.#dbClient.query(
-                'SELECT id, order_id FROM order_items WHERE id = ?', [itemId]
+            connection = await this.#pool.getConnection();
+            await connection.beginTransaction();
+            
+            // Проверяем существование целевого заказа
+            const targetOrderCheck = await connection.query(
+                'SELECT id FROM orders WHERE id = ?', 
+                [targetOrderId]
+            );
+            
+            if (!targetOrderCheck || targetOrderCheck.length === 0) {
+                await connection.rollback();
+                connection.release();
+                return Promise.reject({
+                    type: DB_USER_ERROR,
+                    error: new Error("Target order not found")
+                });
+            }
+            
+            const item = await connection.query(
+                'SELECT id, order_id FROM order_items WHERE id = ? FOR UPDATE', 
+                [itemId]
             );
 
             const itemRow = item?.[0];
-            if (!itemRow){
+            if (!itemRow) {
+                await connection.rollback();
+                connection.release();
                 return Promise.reject({
                     type: DB_USER_ERROR,
                     error: new Error("Order item not found")
                 });
             }
 
-            await this.#dbClient.query(
+            await connection.query(
                 'UPDATE order_items SET order_id = ? WHERE id = ?',
                 [targetOrderId, itemId]
             );
 
-            await this.#dbClient.query('COMMIT');
-        } catch (err){
-            await this.#dbClient.query('ROLLBACK');
-            return Promise.reject();
+            await connection.commit();
+            connection.release();
+            
+        } catch (err) {
+            if (connection) {
+                try {
+                    await connection.rollback();
+                } catch (rollbackErr) {
+                    console.error('Rollback error:', rollbackErr.message);
+                }
+                connection.release();
+            }
+            
+            return Promise.reject({
+                type: DB_INTERNAL_ERROR,
+                error: new Error("Failed to move order item"),
+                details: err.message
+            });
         }
     }
-}
+}
\ No newline at end of file