帮我写个A类的增删改查
时间: 2023-12-25 15:05:18 浏览: 25
以下是针对A类的增删改查的示例代码:
1. 添加新的A类记录:
```
public void addA(A a) {
// 将A类对象添加到数据库中
// 数据库操作语句
String sql = "INSERT INTO A (name, age, gender) VALUES (?,?,?)";
// 执行语句
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setString(1, a.getName());
pstmt.setInt(2, a.getAge());
pstmt.setString(3, a.getGender());
pstmt.executeUpdate();
pstmt.close();
}
```
2. 删除指定A类记录:
```
public void deleteA(int id) {
// 从数据库中删除指定id的A类记录
// 数据库操作语句
String sql = "DELETE FROM A WHERE id = ?";
// 执行语句
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, id);
pstmt.executeUpdate();
pstmt.close();
}
```
3. 更新指定A类记录:
```
public void updateA(A a) {
// 更新指定id的A类记录
// 数据库操作语句
String sql = "UPDATE A SET name = ?, age = ?, gender = ? WHERE id = ?";
// 执行语句
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setString(1, a.getName());
pstmt.setInt(2, a.getAge());
pstmt.setString(3, a.getGender());
pstmt.setInt(4, a.getId());
pstmt.executeUpdate();
pstmt.close();
}
```
4. 查询指定A类记录:
```
public A getA(int id) {
// 查询指定id的A类记录
// 数据库操作语句
String sql = "SELECT * FROM A WHERE id = ?";
// 执行语句
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, id);
ResultSet rs = pstmt.executeQuery();
// 处理结果集
A a = null;
if (rs.next()) {
a = new A();
a.setId(rs.getInt("id"));
a.setName(rs.getString("name"));
a.setAge(rs.getInt("age"));
a.setGender(rs.getString("gender"));
}
rs.close();
pstmt.close();
return a;
}
```
5. 查询所有A类记录:
```
public List<A> getAllA() {
// 查询所有A类记录
// 数据库操作语句
String sql = "SELECT * FROM A";
// 执行语句
PreparedStatement pstmt = conn.prepareStatement(sql);
ResultSet rs = pstmt.executeQuery();
// 处理结果集
List<A> list = new ArrayList<>();
while (rs.next()) {
A a = new A();
a.setId(rs.getInt("id"));
a.setName(rs.getString("name"));
a.setAge(rs.getInt("age"));
a.setGender(rs.getString("gender"));
list.add(a);
}
rs.close();
pstmt.close();
return list;
}
```