java程序中数据库连接及数据处理基本语句

1.数据库连接：

public void initialConnection(){

try{

Class.forName("org.gjt.mm.mysql.Driver");

conn = DriverManager.getConnection("jdbc:mysql://" + host + "/smsdb","root","123");

stmt = conn.createStatement();

System.out.println("成功！");

}catch(SQLException ea){ea.printStackTrace();}

catch(ClassNotFoundException ea){ea.printStackTrace();}

}

2.数据查询：

try{

this.initialConnection();

//查询数据库获得当前用户所属学院的名称

String sql1 = "select coll_name from college where coll_id='" + coll_id + "'";

rs = stmt.executeQuery(sql1);

if(rs.next()){

String coll_name = new String(rs.getString(1).getBytes("ISO-8859-1"));

jcb[4].addItem(coll_name);

}

rs.close(); this.closeConn();

}catch(Exception ea){ea.printStackTrace();}

3.数据更新：

try{

//得到数据库连接

this.initialConnection();

//SQL语句

String sql = "update user_teacher set pwd='" + newPwd + "' where tea_name='" + user_name + "' and pwd ='" + oldPwd + "'";

//执行更新

int i = stmt.executeUpdate(sql);

//如果更新失败，弹出错误消息

if(i == 0){

JOptionPane.showMessageDialog(this, "修改失败，请检查您的用户名或密码是否正确","错误",JOptionPane.ERROR_MESSAGE);

}

else if(i == 1){

JOptionPane.showMessageDialog(this, "密码修改成功", "提示", JOptionPane.INFORMATION_MESSAGE);

}

this.closeConn();

}catch(Exception ea){ea.printStackTrace();}

4.数据连接关闭：

public void closeConn(){

try{

if(rs != null){rs.close();}

if(stmt != null){stmt.close();}

if(conn != null){conn.close();}

}catch(SQLException ea){ea.printStackTrace();}

}