jsp jstl sql与mysql中的奇怪行为 [英] jsp jstl sql strange behaviour with as in mysql

问题描述

在mysql中，我具有一个存储过程，该存储过程具有类似sql的SQL:

In mysql i m having a stored procedure which has a sql like:

select firstname as i_firstname , lastname as i_lastname from roleuser 
where user_id = uid ;

我正在使用jstl代码获取值:-

I m using a jstl code to get the values: -

<sql:query var="comm_codes" dataSource="jdbc/myDatasource">
    call sp_select_username(?);
    <sql:param>${user_id}</sql:param>
</sql:query>

<c:forEach var="rows" items="${comm_codes.rows}">
    ${rows.i_firstname} ${rows.i_lastname}
</c:forEach>

但是此代码不会返回任何内容，但是当将上面的代码 $ {rows.i_firstname} 替换为 $ {rows.firstname} 时，我得到了正确的值.

But this code does not return anything but when the replace the above code ${rows.i_firstname} with ${rows.firstname} i get the correct values.

jstl出问题了，这是可复制的还是我的错...

Anything wrong with jstl, is this replicable or my fault here...

问题还发布了此处和此处

谢谢

推荐答案

我知道这是一篇旧文章，但我也遇到了此问题.在这里讨论: http://forums.mysql.com/read.php?39,432843,432862#msg-432862

I know it is an old post, but I encountered this problem as well. It is discussed here: http://forums.mysql.com/read.php?39,432843,432862#msg-432862

重要的是，mysql论坛中的张贴者指出

Importantly, the poster in the mysql forum states

ResultSetMetaData.getColumnName()将返回列的实际名称，如果存在

这提供了一种解决方法-防止存在列名，因此必须使用别名.例如，原始海报的存储过程可以修改为

This provides a work-around - prevent the column name from existing, so that the alias must be used. As an example, the original poster's stored procedure could be modified to be

select concat(first name,'') as i_firstname , 
       concat(lastname,'') as i_lastname from roleuser 
where user_id = uid ; 

在这种情况下，原始列现在未知，并且使用别名.我已经在类似的情况下在我的系统上对其进行了测试.同样，如果需要为int使用别名，则可以尝试SELECT(id + 0)AS id_alias.我敢肯定，大多数列类型都有类似的解决方案.希望这会有所帮助.

In this case, the original column is now unknown, and the alias is used. I've tested this on my system in a similar situation at it worked. Likewise, if you need to use an alias for an int, you can try SELECT (id+0) AS id_alias. I'm sure most column types have similar solutions. Hope this helps.

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