sql - CASE 内的多个 ORDER BY

Question

我有一个 select 语句，其结尾如下:

order by case @pcsort
            when '' then compcode asc
            else received asc, compcode asc
        end

基本上我需要它，如果 @pcsort是 ' ' 则按 compcode 排序，否则按 received 排序和compcode按此顺序。

有什么想法吗？

Answer 1

这将实现您想要的假设数据类型兼容

order by
    case @pcsort
            when '' then compcode
            else received
    end ASC, 
    compcode ASC

更一般地说，假设数据类型兼容，每个排序列需要一个 CASE

order by
    case @pcsort
            when '' then compcode
            else received
    end ASC, 
    case @pcsort
           --safe to sort on same column agaon , or use a constant
            when '' then compcode or <constant of same type as compcode>
            else compcode
    end ASC

当数据类型不兼容时，您需要更多的情况和大量的常量

order by
case @pcsort
        when '' then compcode
        else <constant of same type as compcode>
end ASC, 
    case @pcsort
        when '' then <constant of same type as received>
        else received
end ASC, 
case @pcsort
        when '' then <constant of same type as compcode>
        else compcode
end ASC