Question

我的select查询中有一个case函数。在这种情况下，我想使用SEC_TO TIME函数将以秒为单位的“ SongLength”转换为mm：ss格式。但是，将此函数放到那里时，我会收到语法错误。

select SongTitle,Artist,SongLength
  case
       when SongLength < 600 then
            sec_to_time(SongLength)
       else
            sec_to_time(SongLength)
  end 
 from Songs, Artists where Songs.ArtistId = Artists.Id 
order by SongTitle;

Answer 1

尝试SongLength作为别名：

select SongTitle,Artist,
(case
when SongLength < 600 then
    sec_to_time(SongLength)
else
    sec_to_time(SongLength)
end) as SongLength 
 from Songs join Artists 
  on ( Songs.ArtistId = Artists.Id ) 
 order by SongTitle;

Answer 2

请参见以下示例，效果很好

select case
    when 400 < 600 then
        sec_to_time(400)
    else
        sec_to_time(300)
    end as col

它返回到输出下方

     col
    00:06:40

因此，如果您的SongLength列的数据类型为数字，那么它应该可以工作

http://www.sqlfiddle.com/#!9/835f61/150

SEC_TO_TIME函数在case函数内中断

2 个答案: