多ORDER BY CASE

Question

內我有一個select語句下面的這結尾：

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 '由compcode'，然後順序，否則爲了通過received並依次compcode。

任何想法？

Answer 1

這將做你想做的假設數據類型相互兼容

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

更一般地，你需要爲每個排序列一個CASE假設數據類型是兼容

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 

如果數據類型是不兼容的，你需要更多的案例和大量的常量

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