增加用户名

首页根据用户名查询出来结果:

 Class.forName("com.mysql.jdbc.Driver");
 Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/spring", "root", "ocsoft");
 
 String sqlQuery = "select count(*) from user where username= ?";
 PreparedStatement psQuery = conn.prepareStatement(sqlQuery);
 psQuery.setString(1,username);
 ResultSet rs = psQuery.executeQuery();
 rs.next();
 int count = rs.getInt(1);//拿到字段值
 if (count > 0) {
  response.sendRedirect("registerFail.jsp");
  psQuery.close();
  conn.close();
  return;
 }

 如果查询出来的值大于零...表明用户名已经存在了.否则反之....添加该用户

	String sql = "insert into user (username,password) values(?,?)";
	PreparedStatement ps = conn.prepareStatement(sql);
	ps.setString(1,username);
	ps.setString(2,password);
	ps.executeUpdate();
	ps.close();
	conn.close();
	
	response.sendRedirect("registerSuccess.jsp");

 

总结:以后编程一般用这种思想编