字符串字段按数字排序解决思路

字符串字段按数字排序
请问，我有一个字符串字段(toc),里面全是数字，希望它按照数字排序，sql语句这样写的
select   CAST(toc   AS   NUMERIC)   from   tt   order   by   toc
但是出错，弹出field   in   orde   by   must   result   set  
请问正确的sql应该怎样写




[解决办法]
select CAST(toc AS NUMERIC) as toc from tt order by toc 也许可以
[解决办法]
SELECT CAST(toc AS NUMERIC) AS Atoc
FROM tt
ORDER BY Atoc
[解决办法]
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