Leftrimming Zero與字符串中包含的字符與字符

Question

我需要編寫一個函數，從varchar列中刪除所有前導零。例如：0300必須變爲300，A0300必須變成A300。第一個退出容易，但我不能得到第二個工作（A0300-> A300）。任何人都可以將我指向正確的方向嗎？

Answer 1

WITH test AS 
(
    SELECT 'A0300' AS code 
    UNION 
    SELECT '0300' 
), 
strip AS (
SELECT code, SUBSTRING(code, PATINDEX('%[0-9]%', code), LEN(code)) AS number 
from test 
) 

select REPLACE(code, number, CAST(number as INT)) 
FROM strip 

Answer 2

在舊版本，其中PATINDEX不起作用，或者如果PATINDEX太慢：

做的情況下，並使用LIKE '[0-9]'/ NOT LIKE '[0-9]'找到正確的分裂點 - 假設知道您的字符串的最大長度，以便您可以根據需要準備多個案例。 您可以在數字開頭找到正確的字符編號，並將右邊的部分作爲INT進行轉義以消除前導0，然後將結果作爲VARCHAR進行轉換，以重新彙總您的前導字母。

會製造類似如下： 選擇 CASE WHEN LEFT（列名，1）NOT LIKE '[0-9]' 和substring（列名，2,1）LIKE '[0-9]' 然後離開（ （列名，2）（LEN（columnname）-2））AS INT）AS VARCHAR（25）） 當左（列名，2）不像'[0-9]'和底層（columnname，3,1）.... END

如果您不確定前導/尾隨空格，您應該用LTRIM（RTRIM（columnname））修剪空格，因爲我們要計算字符可能更可靠。

Answer 3

下面的潰爛代碼演示了一種方式，用一個平凡的狀態機遍歷字符串，並解析出邪惡的零。要查看內部發生了什麼，可以在CTE之後切換select。

-- Sample data. 
declare @Samples as Table (SampleId Int Identity, Sample VarChar(100)); 
insert into @Samples (Sample) values 
    ('0300'), ('A0300'), ('zer0'), ('0'), ('000'), ('00000Q050098'); 
select * from @Samples; 

-- Fiendish thingy. 
declare @False as Bit = 0, @True as Bit = 1; 
with 
    Characters as (
    select SampleId, Sample, 1 as Position, Substring(Sample, 1, 1) as Character, 
     case when Substring(Sample, 1, 1) = '0' then @True else @False end as IsZero, 
     case when Substring(Sample, 1, 1) = '0' then @True else @False end as FirstZeroes 
     from @Samples 
    union all 
    select SampleId, Sample, Position + 1, Substring(Sample, Position + 1, 1), 
     case when Substring(Sample, Position + 1, 1) = '0' then @True else @False end, 
     case 
     when FirstZeroes is NULL then NULL -- We're done with this string. 
     when FirstZeroes = @True and Substring(Sample, Position + 1, 1) <> '0' then NULL -- We just finished with this string. 
     when Substring(Sample, Position + 1, 1) = '0' then @True -- We're (still) going with this string. 
     else @False end 
     from Characters 
     where Position < Len(Sample)) 
-- select * from Characters order by SampleId, Position; -- Use this statement to see the intermediate results. 
    select C.SampleId, C.Sample, 
    Coalesce(Stuff((select Character from Characters where SampleId = C.SampleId and (FirstZeroes = 0 or FirstZeroes is NULL) order by Position for XML path(''), type).value('.[1]', 'VarChar(max)'), 1, 0, ''), '') as DeZeroed 
    from Characters as C 
    group by SampleId, Sample