jsp jstl sql 与 mysql 中的 as 的奇怪行为

发布于 2024-10-17 13:01:25 字数 897 浏览 3 评论 0原文

在mysql中，我有一个存储过程，其中有一个sql，例如：

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

我使用jstl代码来获取值：-

<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，但是当替换上面的代码时 ${rows.i_firstname} 和 ${rows.firstname} 我得到了正确的值。

jstl 有什么问题吗，这是可复制的还是我的错...

问题也发布了此处和此处< /a>

谢谢

原文

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 ;

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>

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.

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

Question also posted here and here

thanks

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谁的年少不轻狂 2024-10-24 13:01:25

我知道这是一个旧帖子，但我也遇到了这个问题。这里讨论： http://forums.mysql.com/ read.php?39,432843,432862#msg-432862

重要的是，mysql 论坛中的海报指出

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 - 防止列名称存在，因此必须使用别名。例如，原始发布者的存储过程可以修改为：

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。我已经在我的系统上在类似的情况下测试了它的工作原理。同样，如果需要为 int 使用别名，可以尝试 SELECT (id+0) AS id_alias。我确信大多数列类型都有类似的解决方案。希望这有帮助。

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

Importantly, the poster in the mysql forum states

ResultSetMetaData.getColumnName() will return the actual name of the column, if it exists

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 ;

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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