fix delete category

mysql-code/Schema.sql

@@ -28,19 +28,6 @@ CREATE TABLE Category (
     Name VARCHAR(255) NOT NULL
 );
 
-CREATE TABLE Product (
-    ProductID INT AUTO_INCREMENT PRIMARY KEY,
-    Name VARCHAR(255) NOT NULL,
-    Price DECIMAL(10, 2) NOT NULL,
-    StockQuantity INT,
-    UserID INT,
-    Description TEXT,
-    CategoryID INT NOT NULL,
-    Date DATETIME DEFAULT CURRENT_TIMESTAMP,
-    FOREIGN KEY (UserID) REFERENCES User (UserID),
-    FOREIGN KEY (CategoryID) REFERENCES Category (CategoryID)
-);
-
 -- Product Entity
 CREATE TABLE Product (
     ProductID INT AUTO_INCREMENT PRIMARY KEY,
@@ -51,7 +38,7 @@ CREATE TABLE Product (
     Description TEXT,
     CategoryID INT,
     Date DATETIME DEFAULT CURRENT_TIMESTAMP,
-    FOREIGN KEY (UserID) REFERENCES User (UserID) ON DELETE SET NULL,
+    FOREIGN KEY (UserID) REFERENCES User (UserID) ON DELETE CASCADE,
     FOREIGN KEY (CategoryID) REFERENCES Category (CategoryID)
 );
 
@@ -73,7 +60,7 @@ CREATE TABLE Review (
         AND Rating <= 5
     ),
     Date DATETIME DEFAULT CURRENT_TIMESTAMP,
-    FOREIGN KEY (UserID) REFERENCES User (UserID) ON DELETE SET NULL,
+    FOREIGN KEY (UserID) REFERENCES User (UserID) ON DELETE CASCADE,
     FOREIGN KEY (ProductID) REFERENCES Product (ProductID) ON DELETE CASCADE
 );
 
@@ -85,7 +72,7 @@ CREATE TABLE Transaction (
     Date DATETIME DEFAULT CURRENT_TIMESTAMP,
     PaymentStatus VARCHAR(50),
     FOREIGN KEY (UserID) REFERENCES User (UserID) ON DELETE CASCADE,
-    FOREIGN KEY (ProductID) REFERENCES Product (ProductID) ON DELETE SET NULL
+    FOREIGN KEY (ProductID) REFERENCES Product (ProductID) ON DELETE CASCADE
 );
 
 -- Recommendation Entity (Many-to-One with User, Many-to-One with Product)