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Question

ID State Name  Department   City 
1 O  George  Sales    Phoenix 
1 N  George  Sales    Denver 
2 O  Michael  Order Process  San diego 
2 N  Michael  Marketing   San jose 

我的情況，我需要上表值轉換爲以下格式轉換更新的列值的表。（考慮頂行是列名）

ID Column  OldValue  New Value 
1 Department Phoenix  Denver 
2 Department Order Process Marketing 
2 City  San diego  San jose 

即：我需要從舊記錄和新記錄中捕獲表格的已更改列值，並將它們記錄在不同的表格中。但問題是，我們有許多表格，列名稱和列的數量對於每個表格都不同。

如果有人來解決方案，將不勝感激..！

預先感謝您。

Answer 1

這是你想要的嗎？

ID Column  OldValue  New Value 
1 City  Phoenix  Denver 
2 Department Order Process Marketing 
2 City  San Diego  San jose 

這裏是動態代碼：

DECLARE @sqlStm varchar(max); 
DECLARE @sqlSelect varchar(max); 

DECLARE @tablename varchar(200); 
SET @tablename = 'testtable'; 

-- Assume table has ID column and State column. 
SET @sqlSelect = '' 
SET @sqlStm = 'WITH old AS 
(
    SELECT * 
    FROM '+@tablename+' 
    WHERE State=''O'' 
), new AS 
(
    SELECT * 
    FROM '+@tablename+' 
    WHERE State=''N'' 
)'; 

    DECLARE @aCol varchar(128) 
    DECLARE curCols CURSOR FOR 
    SELECT column_name 
    FROM information_schema.columns 
    WHERE table_name = @tablename 
     AND UPPER(column_name) NOT IN ('ID','STATE') 

    OPEN curCols 
    FETCH curCols INTO @aCol 

    WHILE (@@FETCH_STATUS = 0) 
    BEGIN 
    SET @sqlStm = @sqlStm + 
     ', changed'+@aCol+' AS 
(
    SELECT n.ID, '''+@aCol+''' AS [Column], o.['+@aCol+'] AS oldValue, n.['+@aCol+'] AS newValue 
    FROM new n 
    JOIN old o ON n.ID = o.ID AND n.['+@aCol+'] != o.['+@aCol+'] 
)' 
    IF LEN(@sqlSelect) > 0 SET @sqlSelect = @sqlSelect + ' UNION ALL ' 

    SET @sqlSelect = @sqlSelect + ' 
SELECT * FROM changed'+@aCol 

    FETCH curCols INTO @aCol 

    END 

    CLOSE curCols 
    DEALLOCATE curCols 

    SET @sqlSelect = @sqlSelect + ' 
ORDER BY id, [Column]' 


    PRINT @sqlStm+@sqlSelect 

    EXEC (@sqlStm+@sqlSelect) 

這在我的測試輸出如下：

WITH old AS 
(
    SELECT * 
    FROM testtable 
    WHERE State='O' 
), new AS 
(
    SELECT * 
    FROM testtable 
    WHERE State='N' 
), changedName AS 
(
    SELECT n.ID, 'Name' AS [Column], o.[Name] AS oldValue, n.[Name] AS newValue 
    FROM new n 
    JOIN old o ON n.ID = o.ID AND n.[Name] != o.[Name] 
), changedDepartment AS 
(
    SELECT n.ID, 'Department' AS [Column], o.[Department] AS oldValue, n.[Department] AS newValue 
    FROM new n 
    JOIN old o ON n.ID = o.ID AND n.[Department] != o.[Department] 
), changedCity AS 
(
    SELECT n.ID, 'City' AS [Column], o.[City] AS oldValue, n.[City] AS newValue 
    FROM new n 
    JOIN old o ON n.ID = o.ID AND n.[City] != o.[City] 
) 
SELECT * FROM changedName UNION ALL 
SELECT * FROM changedDepartment UNION ALL 
SELECT * FROM changedCity 
ORDER BY id, [Column] 

---

原來的答覆如下：

我會做像這樣 - 因爲我認爲它更清晰比其他方式可能會更快：

with old as 
(
    Select ID, Name,Department,City 
    From table1 
    Where State='O' 
), new as 
(
    Select ID, Name,Department,City 
    From table1 
    Where State='N' 
), oldDepartment as 
(
    Select ID, 'Department' as Column, o.Department as oldValue, n.Department as newValue 
    From new 
    join old on new.ID = old.ID and new.Department != old.Department 
), oldCity as 
(
    Select ID, 'City' as Column, o.City as oldValue, n.City as newValue 
    From new 
    join old on new.ID = old.ID and new.City != old.City 
) 
select * from oldDepartment 
union all 
select * from oldCity 

取決於許多因素（表和索引等的大小），它實際上可能比使用樞軸或情況或分組更快。這真的取決於你的數據。如果這是一次性運行，我只是爲了最簡單的方式去尋找。

Answer 2

最乾淨的方法可能是取消數據，然後使用聚合。這確實需要爲每個表進行自定義編碼，您可以通過使用某種形式的動態SQL進行推廣。

爲了您的具體的例子，這裏是做什麼的說明：

select id, col, 
     max(case when OldNew = 'Old' then value end) as OldValue, 
     max(case when OldNew = 'New' then value end) as NewValue 
from ((select ID, OldNew, 'Name' as col, Name as value 
     from t 
    ) union all 
     (select ID, OldNew, 'Department' as col, Department as value 
     from t 
    ) union all 
     (select ID, OldNew, 'City' as col, City as value 
     from t 
    ) 
    ) unpvt 
group by id, col 
having max(value) <> min(value) and max(value) is not null; 

這是用於說明目的。與使用union all相比，可以更有效地完成untivot，特別是在有很多掃描的情況下。這裏是一個更有效的版本，雖然確切的語法取決於數據庫：

select id, col, 
     max(case when OldNew = 'Old' then value end) as OldValue, 
     max(case when OldNew = 'New' then value end) as NewValue 
from (select ID, OldNew, cols.col, 
      (case when cols.col = 'Name' then Name 
        when cols.col = 'Department' then Department 
        when cols.col = 'City' then City 
       end) as value 
     from t cross join 
      (select 'Name' as col union all select 'Department' union all select 'City') cols 
    ) unpvt 
group by id, col 
having max(value) <> min(value) and max(value) is not null; 

這是更有效，因爲它通常只掃描表一次，而不是每進行一次列在union all版本。

在任一版本中，都有一個隱含假設，即所有列都具有相同的字符類型。這隱含在您要轉換爲的格式中，其中所有值都位於單個列中。