JDBC增删改查 代码演示

(2)连接的获取

　　在操作前必须先获取与数据库的连接。

　　driver、url的格式同样可以参考各种数据库对应的jar包、驱动类名和URL格式。

private static Connection getConn() {    String driver = "com.mysql.jdbc.Driver";    String url = "jdbc:mysql://localhost:3306/samp_db";    String username = "root";    String password = "";    Connection conn = null;    try {        Class.forName(driver); //classLoader,加载对应驱动        conn = (Connection) DriverManager.getConnection(url, username, password);    } catch (ClassNotFoundException e) {        e.printStackTrace();    } catch (SQLException e) {        e.printStackTrace();    }    return conn;}

 

(3)insert

private static int insert(Student student) {    Connection conn = getConn();    int i = 0;    String sql = "insert into students (Name,Sex,Age) values(?,?,?)";    PreparedStatement pstmt;    try {        pstmt = (PreparedStatement) conn.prepareStatement(sql);        pstmt.setString(1, student.getName());        pstmt.setString(2, student.getSex());        pstmt.setString(3, student.getAge());        i = pstmt.executeUpdate();        pstmt.close();        conn.close();    } catch (SQLException e) {        e.printStackTrace();    }    return i;}

 

(4)update

private static int update(Student student) {    Connection conn = getConn();    int i = 0;    String sql = "update students set Age='" + student.getAge() + "' where Name='" + student.getName() + "'";    PreparedStatement pstmt;    try {        pstmt = (PreparedStatement) conn.prepareStatement(sql);        i = pstmt.executeUpdate();        System.out.println("resutl: " + i);        pstmt.close();        conn.close();    } catch (SQLException e) {        e.printStackTrace();    }    return i;}

 

(5)select

　　以select * from XXX为例。

private static Integer getAll() {    Connection conn = getConn();    String sql = "select * from students";    PreparedStatement pstmt;    try {        pstmt = (PreparedStatement)conn.prepareStatement(sql);        ResultSet rs = pstmt.executeQuery();        int col = rs.getMetaData().getColumnCount();        System.out.println("============================");        while (rs.next()) {            for (int i = 1; i <= col; i++) {                System.out.print(rs.getString(i) + "\t");                if ((i == 2) && (rs.getString(i).length() < 8)) {                    System.out.print("\t");                }             }            System.out.println("");        }            System.out.println("============================");    } catch (SQLException e) {        e.printStackTrace();    }    return null;}

 

(6)delete

private static int delete(String name) {    Connection conn = getConn();    int i = 0;    String sql = "delete from students where Name='" + name + "'";    PreparedStatement pstmt;    try {        pstmt = (PreparedStatement) conn.prepareStatement(sql);        i = pstmt.executeUpdate();        System.out.println("resutl: " + i);        pstmt.close();        conn.close();    } catch (SQLException e) {        e.printStackTrace();    }    return i;}