数字小于4时补充0

Question

当数字少于4时，那么在数字前补充0，在sqlserver中怎么做？ 我的sql是

SELECT 
  tt.Ddate as PzDate,
  cast(ltrim(RTRIM(tt.VouchClassCode)) +'-'+cast (tt.VouchNo as varchar(100))  as varchar(100))  as PzZh,
  t.Digest as Zy,
  t.Ccode as Kmbm,
  ttt.Cname as Kmname,
  t.Jfje as Jfje,
  t.Dfje as Dfje,
  tt.Bill as Zhidan,
  tt.Checker as Shenhe, 
  tt.Book as Jizhang,
  tt.VouchSource as Pzlaiy 
  FROM [TOBROS_CWT].[dbo].[Cwzz_AccVouchSub] t
  left join Cwzz_AccVouchMain tt 
  on t.VouchId = tt.VouchId
  left join Cwzz_AccCode ttt 
  on t.Ccode = ttt.Ccode
  order by t.VouchId ,tt.Ddate,tt.VouchNo      

请看图片，我想改变PzZh格式， 例如“银-1”到“银-0001” 该怎么做，谢谢。

Answer 1

尝试使用CASE表达式和RIGHT，如下所示：

cast(ltrim(RTRIM(tt.VouchClassCode)) +'-'+
    CASE WHEN tt.VouchNo < 10000 THEN
        RIGHT('0000' + cast (tt.VouchNo as varchar(100)),4)
    ELSE
        cast (tt.VouchNo as varchar(100))
    END
as varchar(100))  as PzZh

Answer 2

如果长度小于4，则可以检查长度，然后添加尾随零

cast(ltrim(RTRIM(tt.VouchClassCode)) +'-'+ 
  Case WHEN len(tt.VouchNo)< 4 Then RIGHT('0000' + cast (tt.VouchNo as varchar(100)),4)  
  Else
  cast (tt.VouchNo as varchar(100)) 

  End  as varchar(100))  as PzZh