关于数据库访问的程序（不少于50行，一个程序行数不够的话可以写两个）并写出注释。
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发布时间：2022-05-29 06:47
共1个回答
热心网友
时间：2023-10-09 21:38
1:对数据库的查询
public List<CartItem> listCartItem(User u) throws ClassNotFoundException,
SQLException {
Class.forName("com.mysql.jdbc.Driver");
Connection c = DriverManager
.getConnection(
"jdbc:mysql://127.0.0.1:3306/shopproject?characterEncoding=GBK",
"root", "admin");
Statement st = c.createStatement();
String s = String
.format(
"select cart_item.*,proct.name from cart join cart_item on cart.id = cart_item.cart_id join proct on cart_item.proct_id = proct.id where cart.user_id = %d",
u.getId());
ResultSet rs = st.executeQuery(s);
List<CartItem> l = new ArrayList<CartItem>(getCount(u));
while (rs.next()) {
CartItem ci = new CartItem();
ci.setId(rs.getInt(1));
ci.setCart_id(rs.getInt(2));
ci.setProct_id(rs.getInt(3));
ci.setProct_name(rs.getString(6));
ci.setAmount(rs.getInt(4));
ci.setPrice(rs.getFloat(5));
l.add(ci);
}
rs.close();
st.close();
c.close();
return l;
}
2:对数据库的操作之增加
public void addCartItem(CartItem ci) throws ClassNotFoundException,
SQLException {
Class.forName("com.mysql.jdbc.Driver");
Connection c = DriverManager
.getConnection(
"jdbc:mysql://127.0.0.1:3306/shopproject?characterEncoding=GBK",
"root", "admin");
Statement st = c.createStatement();
String s = String
.format(
"insert into cart_item (cart_id,proct_id,amount,price) values (%d,%d,%d,%f)",
ci.getCart_id(), ci.getProct_id(), ci.getAmount(), ci
.getPrice());
st.execute(s);
st.close();
c.close();
}
3：对数据库的操作之删除
public void deleteCartItem(int id) throws ClassNotFoundException,
SQLException {
Class.forName("com.mysql.jdbc.Driver");
Connection c = DriverManager
.getConnection(
"jdbc:mysql://127.0.0.1:3306/shopproject?characterEncoding=GBK",
"root", "admin");
Statement st = c.createStatement();
String s = String.format("delete from cart_item where id = %d", id);
st.execute(s);
st.close();
c.close();
}
够了吧，记得给分哦，写这么多不容易啊
