CASE中的多个ORDER BY

Question

我有一个select语句，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''，那么按compcode排序，否则按received和compcode按顺序排序。

有什么想法吗？

Answer 1

这将做你想要的假设数据类型是兼容的

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

如果数据类型不兼容，则需要更多案例和大量常量

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