java jdbc连接和使用详细介绍

  Class.from("com.mysql.jdbc.Driver");

//导包使用 java.sql.*；String jdbc="jdbc:mysql://localhost:3306/student?user=root&password=&characterEncoding=utf-8";//student是表名Connection conn = DriverManager.getConnection(jdbc);

 conn.close();

Statemant st = conn.createStatemant(); int row = st.executeUpdate(sql语句);//不能做查询操作。

String sql = "insert into " + TABLENAME+ "(name,subject,score) values(?,?,?)";PrepareStatement pt = conn.prepareStatement(sql); //给每一位占位符设置值,下标从1开始 pt.setString(1,score.getName()); pt.setString(2.score.getSubject());pt.setDouble(3,score.getScore()); //使用无参的方法pt.executeUpdate();

static List<Score> queryScore(Connection pconn, Score pScore)      throws SQLException {    ArrayList<Score> mlist = new ArrayList<>();    String sql = "select * from " + TABLENAME + " where name = ?";    PreparedStatement ps = pconn.prepareStatement(sql);    ps.setString(1, pScore.getName());    ResultSet rs = ps.executeQuery();    while (rs.next()) {      // 这里可以通过rs获取所有结果      String subject = rs.getString("subject");      int id = rs.getInt("id");      double score = rs.getDouble("score");      mlist.add(new Score(id, pScore.getName(), subject, score));    }    return mlist;  }

//建立数据库连接类public class DAO {  // 放问数据库的链接地址  static String jdbc = "jdbc:mysql://localhost:3306/student?user=root&password=&characterEncoding=utf-8";  // 打开链接  public static Connection connection() {    // 使用JDBC的步骤    // 1. 加载JDBC驱动    try {      // 类的全名 包名+类名      Class.forName("com.mysql.jdbc.Driver");      // 2. 连接数据库      Connection conn = DriverManager.getConnection(jdbc);      return conn;    } catch (Exception e) {      System.out.println("驱动加载失败");      return null;    }  }}//分数类public class Score {  String name;  String id;  String subject;  double score;  public Score(String name, String subject, double score) {    super();    this.name = name;    this.subject = subject;    this.score = score;  }  @Override  public String toString() {    return "Score [name=" + name + ", id=" + id + ", subject=" + subject        + ", score=" + score + "]";  }  public Score(String name, String id, String subject, double score) {    super();    this.name = name;    this.id = id;    this.subject = subject;    this.score = score;  }  public String getName() {    return name;  }  public void setName(String name) {    this.name = name;  }  public String getId() {    return id;  }  public void setId(String id) {    this.id = id;  }  public String getSubject() {    return subject;  }  public void setSubject(String subject) {    this.subject = subject;  }  public double getScore() {    return score;  }  public void setScore(double score) {    this.score = score;  }}//实现类public class Test {  public static String TABLENAME = "score";  public static void main(String[] args) {    try {      Connection conn = DAO.connection();      if (conn != null) {        System.out.println("链接上了");        // createTable(conn);        // 插入一条记录        // Score score = new Score("李四 ", "Android", 98);        // System.out.println(addScore2(conn, score));        // deleteScore(conn, score);        // updateScore(conn, score);        List<Score> list = queryScoreByName(conn, "王五"); //queryAllScore(conn);        for (Score score : list) {          System.out.println(score);        }        conn.close();      } else {        System.out.println("链接失败 ");      }    } catch (SQLException e) {      e.printStackTrace();    }  }  // 创建一张表  public static boolean createTable(Connection conn) {    // 开始执行sql语句    String sql = "create table "        + TABLENAME        + "(id integer primary key auto_increment,name varchar(3) not null,subject varchar(20) not null,score double)";    // 要执行一条语句，需要一个执行的类 Statement    try {      Statement st = conn.createStatement();      int result = st.executeUpdate(sql);      System.out.println(result);      if (result != -1)        return true;    } catch (SQLException e) {      e.printStackTrace();    }    return false;  }  // 添加一条记录  public static boolean addScore(Connection conn, Score score)      throws SQLException {    String sql = "insert into " + TABLENAME        + "(name,subject,score) values('" + score.getName() + "','"        + score.getSubject() + "'," + score.getScore() + ")";    System.out.println(sql);    Statement st = conn.createStatement();    int row = st.executeUpdate(sql);    if (row > 0)      return true;    return false;  }  // 添加一条记录2  public static boolean addScore2(Connection conn, Score score)      throws SQLException {    // 占位符?来代替需要设置的参数    String sql = "insert into " + TABLENAME        + "(name,subject,score) values(?,?,?)";    PreparedStatement ps = conn.prepareStatement(sql);    // 必须给定？所代表的值    ps.setString(1, score.getName());    ps.setString(2, score.getSubject());    ps.setDouble(3, score.getScore());    // 调用无参的方法    int row = ps.executeUpdate();    if (row > 0)      return true;    return false;  }  public static boolean deleteScore(Connection conn, Score score)      throws SQLException {    String sql = "delete from " + TABLENAME + " where name=? and subject=?";    // 创建PrepareStatement    PreparedStatement ps = conn.prepareStatement(sql);    ps.setString(1, score.getName());    ps.setString(2, score.getSubject());    // ps.setDouble(3, score.getScore());    // 执行    int row = ps.executeUpdate();    System.out.println(row);    if (row > 0)      return true;    return false;  }  public static boolean updateScore(Connection conn, Score score)      throws SQLException {    // 修改 score人他的科目的成绩    String sql = "update " + TABLENAME        + " set score=? where name=? and subject=?";    PreparedStatement ps = conn.prepareStatement(sql);    ps.setDouble(1, score.getScore());    ps.setString(2, score.getName());    ps.setString(3, score.getSubject());    int row = ps.executeUpdate();    System.out.println(row);    if (row > 0)      return true;    return false;  }  public static List<Score> queryAllScore(Connection conn)      throws SQLException {    String sql = "select * from " + TABLENAME;    // 开始查询    Statement st = conn.createStatement();    ResultSet rs = st.executeQuery(sql);    List<Score> list = new ArrayList<Score>();    while (rs.next()) {      // 这里可以通过rs获取所有结果      String id = rs.getString("id");      String name = rs.getString("name");      String subject = rs.getString("subject");      double score = rs.getDouble("score");      list.add(new Score(name, id, subject, score));    }    // 结束    return list;  }  public static List<Score> queryScoreByName(Connection conn, String name)      throws SQLException {    String sql = "select * from " + TABLENAME + " where name=?";    PreparedStatement pt = conn.prepareStatement(sql);    pt.setString(1, name);    ResultSet rs = pt.executeQuery();    List<Score> list = new ArrayList<>();    while (rs.next()) {      String subject = rs.getString("subject");      String id = rs.getString("id");      double score = rs.getDouble("score");      list.add(new Score(name, id, subject, score));    }    return list;  }