在SQL語句中動態傳遞表名的T-SQL

Question

在T-SQL中從遊標讀取表名的代碼如下。

但我在WITH語句內的範圍表名稱變量有問題。

我可以運行此代碼時，我明確地將dbo.@sys_name設置爲同義詞名稱，如dbo.mysysnonym，但當我把它作爲變量名稱如dbo.@syn_name它不起作用。

-- drop duplicates records from synonyms 
DECLARE @syn_name varchar(50) 

DECLARE s_cursor CURSOR FOR 
    SELECT name 
    FROM sys.synonyms 
    WHERE base_object_name LIKE 'xyz%' 

OPEN s_cursor; 

FETCH NEXT FROM s_cursor INTO @syn_name; 

WHILE @@FETCH_STATUS = 0 
BEGIN 

    FETCH NEXT FROM s_cursor INTO @syn_name; 

    WITH dedupTable AS 
    (
     SELECT 
      sys_id, 
      row_number() OVER (PARTITION BY sys_id ORDER BY sys_id) AS nr 
     FROM 
      dbo.@syn_name 
    ) 
    DELETE FROM dedupTable 
    WHERE nr > 1 
END; 

CLOSE s_cursor 
DEALLOCATE s_cursor 

Answer 1

據我所知，你不能使用變量作爲表名，所以dbo.@syn_name不會在FROM條款工作。相反，您將不得不使用Dynamic SQL。

喜歡的東西：

... 
FETCH NEXT FROM s_cursor INTO @syn_name; 
DECLARE @sql nvarchar(4000) 

SET @sql = N' 
    WITH dedupTable 
    AS ( 
     SELECT sys_id, row_number() 
     OVER (PARTITION BY sys_id ORDER BY sys_id ) AS nr 
     FROM dbo.' + @syn_name + ' 
    ) 
    DELETE FROM dedupTable 
    WHERE nr > 1' 

EXEC sp_executesql @sql