当前位置: 代码迷 >> Java Web开发 >> 怎么验证用户名存在
  详细解决方案

怎么验证用户名存在

热度:842   发布时间:2013-02-25 21:18:36.0
求教:如何验证用户名存在
我想实现登录时验证用户名是否存在于数据库,如果不在count为0的话抛出异常。求指点。应该还有错的地方,请宽容菜鸟的无知。

Connection conn = DBUtils.getConnection();

String queryUN = "SELECT count(1) FROM my_user where username=?";
PreparedStatement pstmt = conn.prepareStatement(queryUN);

 
  if( ){
  throw new Exception("账号名不存在");
  }
}


------解决方案--------------------------------------------------------
ResultSet rs = null;
rs = pstmt.executeQuery();

int j=0;
while (rs.next()) {
 j=1;
}



if(j==0){
throw new Exception("账号名不存在");
}
------解决方案--------------------------------------------------------
String userName = ...
Connection conn = DBUtils.getConnection();
ResultSet rs = null;
String queryUN = "SELECT count(1) FROM my_user where username=?";
PreparedStatement pstmt = conn.prepareStatement(queryUN);
pstmt.setString(1,userName);
rs = pstmt.executeQuery();

  
 if(rs.next() ){
if ( rs.getInt(1) == 0) ) {
throw new Exception("账号名不存在");
}
 } 

------解决方案--------------------------------------------------------
Java code
public Boolean queryUser() throws Exception{Connection conn = DBUtils.getConnection();String queryUN = "SELECT count(1) FROM my_user where username=?";preparedstatement pstmt = conn.preparestatement(queryUN);pstmt.setstring(1,"放你要查的用户名");resultset rs = pstmt.executequery();if(rs.next()){System.out.print("用户名存在");return true;}else{System.out.print("账号名不存在");return false;}rs.close();pstmt.close();conn.close();}
  相关解决方案