是否可以遍历我的 SQL 数据库中的每个 table 并找到其他行中未使用的记录？ （PK/FK 检查）

Question

我想编写一个 SQL 脚本来指出我的整个数据库中的哪些记录没有被其他 table 用作参考。

例如，如果我有一个“评论”table，我想找出我的table中哪些记录没有在 Users、nor 和 Posts 中有关系条目，但没有指定这些 tables按名字。 类似于：

'COLLECT ALL TABLES'
   'LOOP OVER EACH ROW IN THIS TABLE'
      'CHECK OTHER TABLES TO SEE IF THIS PARTICULAR PK_ID IS PRESENT AS A FOREIGN KEY'
         'IF FOUND NOT FOUND'
            'DELETE THIS ROW FROM THIS TABLE'

我知道如何执行 'IF NOT FOUND' 和 'DELETE' 部分，但我很难找到前三个步骤。 欢迎任何想法 and/or 有用的提示或链接。 我很高兴分享我的脚本作为对此 post 完成后的评论，因为我认为它对许多 SQL 开发人员有用。

Answer 1

我想到了自己写脚本，这里是（使用动态SQL）

我有 185 个表和 ~190.000 个描述条目，在执行此脚本后我得到了 ~15.000 个描述行。 （问题是在更改对象的描述时创建了一个新的描述，而不是更新它。在修复了代码中的这个错误后，我在数据库上使用了）。该脚本需要大约 3 个小时才能完成。

USE [YOUR_DATABASE]

PRINT 'BEGIN SCRIPT'


-- put all the tables in your database in a table (where we will perform a cursor on)
SELECT TABLE_NAME INTO ALL_TABLES
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE = 'BASE TABLE' AND TABLE_CATALOG='YOUR_DATABASE' 

-- delete non relevant entities in ALL_TABLES table
delete from ALL_TABLES where TABLE_NAME = 'ALL_TABLES'  -- delete the 'all_tables' table
delete from ALL_TABLES where TABLE_NAME = 'DESCRIPTION' -- your to-check table

-- hide rowcounts
set nocount on


-- Variables to use in the cursors
DECLARE 
    @tableName NVARCHAR(MAX), 
    @descriptionId   INT,
    @descriptionInUse BIT;



-- cursor to get all the entities from ALL_TABLES
DECLARE cursor_allTables CURSOR
FOR SELECT 
        TABLE_NAME
    FROM 
        dbo.ALL_TABLES;


-- cursor to get all the entities out of your to-check table ( mine was Description )
DECLARE cursor_descriptionCleanUp CURSOR
FOR SELECT 
        Id
    FROM 
        dbo.Description;



-- start iterating over descriptions
OPEN cursor_descriptionCleanUp;
FETCH NEXT FROM cursor_descriptionCleanUp INTO 
    @descriptionId;

    
WHILE @@FETCH_STATUS = 0
    BEGIN
        -- set BIT to check if description is in use
        set @descriptionInUse = 0;
        -- start iterating over ALL_TABLE rows
        OPEN cursor_allTables;
            FETCH NEXT FROM cursor_allTables INTO 
                @tableName;
            WHILE @@FETCH_STATUS = 0 AND @descriptionInUse= 0
                BEGIN
                    -- check if this table has a DescriptionId
                    IF COL_LENGTH('dbo.'+@tableName, 'DescriptionId') IS NOT NULL
                        BEGIN
                            -- check the table
                            DECLARE @sql as nvarchar(MAX);
                            DECLARE @rowCount as int; 
                            SET @sql = 'SELECT DescriptionId FROM '+ @tableName+' where DescriptionId = '+ CAST(@descriptionId as nvarchar(MAX))
                            EXEC (@sql)
                            SELECT @rowCount = @@ROWCOUNT;
                            
                            -- If EXEC (@sql) returned more than 0 rows, this Description row is in use in a table -> mark it as used 
                            IF @rowCount > 0
                                BEGIN
                                    set @descriptionInUse= 1;
                                END
                        END
                        
                    FETCH NEXT FROM cursor_allTables INTO 
                        @tableName;
                END;
            
        CLOSE cursor_allTables;
        
    --if description row is not in use -> delete this row
        IF @descriptionInUse = 0
            BEGIN
                DELETE FROM Description where Id = @descriptionId;
                PRINT 'DELETE DESCRIPTION WITH ID: ' + CAST(@descriptionId as nvarchar(MAX))
                PRINT'----------------------------------------------'
            END

            -- fetch next Description Id  from Descriptions
        FETCH NEXT FROM cursor_descriptionCleanUp INTO 
            @descriptionId;
    END;

CLOSE cursor_descriptionCleanUp;

-- clean up 
DEALLOCATE cursor_descriptionCleanUp;
DEALLOCATE cursor_allTables;
drop table ALL_TABLES
-- set nocount back to on 
set nocount off

希望对其他人有帮助:-)