JDBC查询 方式 java， sql， select，数据库

JDBC查询 方式 java， sql， select，数据库 数据库 1.代码优化 1.查询一个（不通用）

public static void queryOne(String sql) throws Exception {

    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/bailiban", "root", "123456");
    Statement stat = conn.createStatement();
    ResultSet query = stat.executeQuery(sql);
    if (query.next()){
        String id = query.getString("id");
        String name = query.getString("name");
        String sex = query.getString("sex");
        String age = query.getString("age");
        System.out.println(id+"--"+name+"--"+sex+"--"+age);
    }
    System.out.println(query.next());
    stat.close();
    conn.close();
}

2.查询多个（不通用）

public static void queryMore(String sql) throws Exception {

    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/bailiban", "root", "123456");
    Statement stat = conn.createStatement();
    ResultSet query = stat.executeQuery(sql);
    while (query.next()){
        String id = query.getString("id");
        String name = query.getString("name");
        String sex = query.getString("sex");
        String age = query.getString("age");
        System.out.println(id+"--"+name+"--"+sex+"--"+age);
    }
    System.out.println(query.next());
    stat.close();
    conn.close();
}

3.通用的代码

public static void queryMorePlus(String sql) throws Exception {

    
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/bailiban", "root", "123456");

    
    Statement stat = conn.createStatement();

    
    ResultSet rs = stat.executeQuery(sql);

    
    ResultSetmetaData md = rs.getmetaData();

    
    int count = md.getColumnCount();

    
    while (rs.next()){
        for (int i = 1; i <= count; i++) {
            Object object = rs.getObject(i);
            System.out.print(object);
        }
        System.out.println();
    }

    
    stat.close();
    conn.close();
}