text: create table student(
    id integer primary key autoincrement,
    name varchar(20) not null,
    age integer not null
  );
  
  insert into student(name,age ) values('jack',26);
  insert into student(name,age ) values('tom',18);
  insert into student(name,age ) values('史泰龙',56);
  insert into student(name,age ) values('泰森',38);
  
  select * from student;
  
  
  drop table Product;
  drop table tb_Product;
  drop table User;
  drop table tb_User;
  drop table tb_order;
  drop table sqlite_sequence;
  
  
  --创建产品表（Product）
  create table tb_product(
    productId integer primary key autoincrement,
    name varchar(50) not null,
    price numeric(5,2) not null
  );
  
  --创建用户表（User）
  create table tb_user(
    userId integer primary key autoincrement,
    name varchar(50) not null
  );
  
  --创建订单表（Order）
  create table tb_order(
    orderId integer primary key autoincrement,
    orderTotalPrice numeric(10,2) not null,
    userId integer,
    foreign key(userId) references tb_user(userId)
  );
  
  --创建订单项表（OrderItem）
  create table tb_orderitem(
    orderItemId integer primary key autoincrement,
    productId integer,
    amount integer,
    orderItemPrice numeric(8,2) not null,
    orderId integer,
    foreign key(productId) references tb_product(productId),
    foreign key(orderId) references tb_order(orderId)
  );
  
  
  StringBuilder stringBuilder = new StringBuilder();
  		stringBuilder
  				.append("create table tb_product(                                   ");
  		stringBuilder
  				.append("  productId integer primary key autoincrement,             ");
  		stringBuilder
  				.append("  name varchar(50) not null,                               ");
  		stringBuilder
  				.append("  price numeric(5,2) not null                              ");
  		stringBuilder
  				.append(");                                                         ");
  		stringBuilder
  				.append("                                                           ");
  		stringBuilder
  				.append("create table tb_user(                                      ");
  		stringBuilder
  				.append("  userId integer primary key autoincrement,                ");
  		stringBuilder
  				.append("  name varchar(50) not null                                ");
  		stringBuilder
  				.append(");                                                         ");
  		stringBuilder
  				.append("                                                           ");
  		stringBuilder
  				.append("create table tb_order(                                     ");
  		stringBuilder
  				.append("  orderId integer primary key autoincrement,               ");
  		stringBuilder
  				.append("  orderTotalPrice numeric(10,2) not null,                  ");
  		stringBuilder
  				.append("  userId integer,                                          ");
  		stringBuilder
  				.append("  foreign key(userId) references tb_user(userId)           ");
  		stringBuilder
  				.append(");                                                         ");
  		stringBuilder
  				.append("                                                           ");
  		stringBuilder
  				.append("create table tb_orderitem(                                 ");
  		stringBuilder
  				.append("  orderItemId integer primary key autoincrement,           ");
  		stringBuilder
  				.append("  productId integer,                                       ");
  		stringBuilder
  				.append("  amount integer,                                          ");
  		stringBuilder
  				.append("  orderItemPrice numeric(8,2) not null,                    ");
  		stringBuilder
  				.append("  orderId integer,                                         ");
  		stringBuilder
  				.append("  foreign key(productId) references tb_product(productId), ");
  		stringBuilder
  				.append("  foreign key(orderId) references tb_order(orderId)        ");
  		stringBuilder
  				.append(");                                                         ");
  
  		db.execSQL(stringBuilder.toString());
  
  
  
  
  
  
  
  