如何比較SQL Server中的兩個字符串元素

Question

我在SQL Server中有兩個字符串。

例如：

declare @str1 as varchar(max) 
declare @str2 as varchar(max) 

set @str1 ='10:00am,2:00pm' 

set @str2 = '10:00am,12:00pm,2:00pm,4:00pm,6:00pm,8:00pm' 

，我想比較兩個字符串，並希望從@str2得到這些元素串不在@str1。

這意味着其結果應該是：

@str3 = '12:00pm,4:00pm,6:00pm,8:00pm' 

Answer 1

試試這個： -

declare @str1 as varchar(max) 
declare @str2 as varchar(max) 

set @str1 ='10:00am,2:00pm' 
set @str2 = '10:00am,12:00pm,2:00pm,4:00pm,6:00pm,8:00pm' 

--the below 2 CTE's are used for splitting the string into different rows 
;with cteStr1(str1) as 
(
SELECT 
RIGHT(LEFT(@str1,Number-1), 
CHARINDEX(',',REVERSE(LEFT(','+@str1,Number-1)))) as str1 
FROM 
master..spt_values 
WHERE 
Type = 'P' AND Number BETWEEN 1 AND LEN(@str1)+1 
AND 
(SUBSTRING(@str1,Number,1) = ',' OR SUBSTRING(@str1,Number,1) = '') 
),cteStr2(str2) as 
    (
    SELECT 
    RIGHT(LEFT(@str2,Number-1), 
    CHARINDEX(',',REVERSE(LEFT(','+@str2,Number-1)))) as str2 
    FROM 
    master..spt_values 
    WHERE 
    Type = 'P' AND Number BETWEEN 1 AND LEN(@str2)+1 
    AND 
    (SUBSTRING(@str2,Number,1) = ',' OR SUBSTRING(@str2,Number,1) = '') 
) 
    Select str2 from cteStr2 
    except 
    select str1 from cteStr1 

Answer 2

試試這個

DECLARE @str1 VARCHAR(MAX) 
DECLARE @str2 VARCHAR(MAX) 

SET @str1 ='10:00am,2:00pm' 
SET @str2 = '10:00am,12:00pm,2:00pm,4:00pm,6:00pm,8:00pm' 

SET @str1 = ',' + @str1 + ',' 
SET @str2 = ',' + @str2 + ',' 

DECLARE @name NVARCHAR(255) 
DECLARE @pos INT 

WHILE CHARINDEX(',', @str1) > 0 
BEGIN 
    SELECT @pos = CHARINDEX(',', @str1) 
    SELECT @name = SUBSTRING(@str1, 1, @pos-1) 

    SELECT @str1 = SUBSTRING(@str1, @pos+1, LEN(@str1)-@pos) 
    IF @name <> '' 
    BEGIN 
     SET @str2 = REPLACE(@str2,','+@name,'') 
    END 
END 

SET @str2 = REPLACE(@str2,','+@name,'') 

SELECT SUBSTRING(@str2, 2, LEN(@str2)-2) AS Result 

Answer 3

嘗試這一個 -

DECLARE 
     @str1 VARCHAR(500) 
    , @str2 VARCHAR(500) 

SELECT 
     @str1 = '10:00am,2:00pm' 
    , @str2 = '10:00am,12:00pm,2:00pm,4:00pm,6:00pm,8:00pm' 

;WITH cte AS 
(
    SELECT 
      id = p.value('(./n)[1]', 'INT') 
     , tm = p.value('(./s)[1]', 'VARCHAR(500)') 
    FROM (
     SELECT field = CAST('<r><s>' + REPLACE(SUBSTRING(t.string + ',', 1, LEN(t.string + ',')), ',', '</s><n>' + CAST(t.id AS VARCHAR(10)) + '</n></r><r><s>') + '</s></r>' AS XML) 
     FROM (
      SELECT string = @str1, id = 1 
      UNION ALL 
      SELECT @str2, 2 
     ) t 
    ) d 
    CROSS APPLY field.nodes('/r') t(p) 
    WHERE t.p.exist('n') = 1 
) 
SELECT tm FROM cte WHERE id = 2 
EXCEPT 
SELECT tm FROM cte WHERE id = 1 

或試試這個 -

;WITH cte2 AS 
(
SELECT 
     t.id 
    , tm = 
     SUBSTRING(
       ',' + t.string + ',' 
      , number + 1 
      , CHARINDEX(',', ',' + t.string + ',', number + 1) - number - 1) 
FROM (
    SELECT string = @str1, id = 1 
    UNION ALL 
    SELECT @str2, 2 
) t 
CROSS JOIN [master].dbo.spt_values n 
WHERE [type] = 'p' 
    AND number <= LEN(',' + t.string + ',') - 1 
    AND SUBSTRING(',' + t.string + ',', number, 1) = ',' 
) 
SELECT tm FROM cte2 WHERE id = 2 
EXCEPT 
SELECT tm FROM cte2 WHERE id = 1