javaee中用preparestatment实现mysql 增删改查preparestatment

在JavaEE中，可以使用PreparedStatement对象来执行MySQL数据库的增删改查操作。PreparedStatement对象是对Statement对象的扩展，可以通过占位符（?）来设置参数，提高SQL语句的执行效率和安全性。

以下是基于PreparedStatement对象实现MySQL的增删改查操作的示例代码：

1. 增加数据：

String sql = "INSERT INTO user(name, age, sex) VALUES(?, ?, ?)";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setString(1, "Tom");
pstmt.setInt(2, 20);
pstmt.setString(3, "M");
int result = pstmt.executeUpdate();

2. 删除数据：

String sql = "DELETE FROM user WHERE id=?";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, 1);
int result = pstmt.executeUpdate();

3. 修改数据：

String sql = "UPDATE user SET age=? WHERE name=?";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, 22);
pstmt.setString(2, "Tom");
int result = pstmt.executeUpdate();

4. 查询数据：

String sql = "SELECT * FROM user WHERE name=?";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setString(1, "Tom");
ResultSet rs = pstmt.executeQuery();
while(rs.next()) {
    int id = rs.getInt("id");
    String name = rs.getString("name");
    int age = rs.getInt("age");
    String sex = rs.getString("sex");
}