mysql 动态条件查询语句

import java.sql.*;

public class DynamicQueryExample {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/mydatabase";
        String user = "username";
        String password = "password";

        try (Connection conn = DriverManager.getConnection(url, user, password)) {
            String baseQuery = "SELECT * FROM users WHERE 1=1";
            StringBuilder queryBuilder = new StringBuilder(baseQuery);
            List<Object> params = new ArrayList<>();

            String name = "John";
            if (name != null && !name.isEmpty()) {
                queryBuilder.append(" AND name = ?");
                params.add(name);
            }

            int age = 25;
            if (age > 0) {
                queryBuilder.append(" AND age = ?");
                params.add(age);
            }

            String sql = queryBuilder.toString();
            try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
                for (int i = 0; i < params.size(); i++) {
                    pstmt.setObject(i + 1, params.get(i));
                }

                ResultSet rs = pstmt.executeQuery();
                while (rs.next()) {
                    System.out.println("ID: " + rs.getInt("id") + ", Name: " + rs.getString("name") + ", Age: " + rs.getInt("age"));
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}