怎样给hql的order by 赋变量

select user from test.User user 
order by :order 

怎样给这个语句的order赋值？
我用

query.setString("order ", "user ."+order);;

出现以下错误

java.sql.SQLException: [Microsoft][SQLServer JDBC Driver][SQLServer]ORDER BY 子句所标识的第 1 个 SELECT 项包含了一个变量，该变量位于标识列位置的表达式中。只有排序依据表达式引用的是列名时，才允许在该表达式中使用变量。
	at com.microsoft.jdbc.base.BaseExceptions.createException(Unknown Source);
	at com.microsoft.jdbc.base.BaseExceptions.getException(Unknown Source);
	at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processErrorToken(Unknown Source);
	at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReplyToken(Unknown Source);
	at com.microsoft.jdbc.sqlserver.tds.TDSRPCRequest.processReplyToken(Unknown Source);
	at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReply(Unknown Source);
	at com.microsoft.jdbc.sqlserver.tds.TDSCursorRequest.openCursor(Unknown Source);
	at com.microsoft.jdbc.sqlserver.SQLServerImplStatement.execute(Unknown Source);
	at com.microsoft.jdbc.base.BaseStatement.commonExecute(Unknown Source);
	at com.microsoft.jdbc.base.BaseStatement.executeQueryInternal(Unknown Source);
	at com.microsoft.jdbc.base.BasePreparedStatement.executeQuery(Unknown Source);
	at org.apache.commons.dbcp.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:179);

怎么办？

顶 顶 顶 顶 顶 顶 顶 顶 顶

出错信息说得很清楚了，只能是列名