Question

我正在努力清理ERP，我需要摆脱对未使用的用户和用户组的引用。有许多外键约束，因此我想确保真正摆脱所有痕迹！

我发现这个整洁的代码来查找我的数据库中具有特定列名的所有表，在这种情况下让我们看一下用户组：

select table_name from information_schema.columns
where column_name = 'GROUP_ID'

结果我可以在40多个表中搜索我未使用的ID ...但这是tedius。所以我想自动执行此操作并创建一个循环遍历所有这些表的查询，并删除Unused_Group列中找到GROUP_ID的行。

在删除任何内容之前我想要显示现有数据，所以我开始使用字符串连接来构建这样的东西：

declare @group varchar(50) = 'Unused_Group'
declare @table1 varchar(50) = 'TABLE1'
declare @table2 varchar(50) = 'TABLE2'
declare @tableX varchar(50) = 'TABLEX'

select @query1 = 'SELECT ''' + rtrim(@table1)  + ''' as ''Table'', '''
+ rtrim(@group) + ''' = CASE WHEN EXISTS (SELECT GROUP_ID FROM ' + rtrim(@table1)
+ ' WHERE GROUP_ID = ''' + rtrim(@group) + ''') then ''MATCH'' else ''-'' end FROM '
+ rtrim(@table1)

select @query2 = [REPEAT FOR @table2 to @tableX]...

EXEC(@query1 + ' UNION ' + @query2 + ' UNION ' + @queryX)

这给了我结果：

TABLE1  |  Match
TABLE2  |  -
TABLEX  |  Match

这适用于我的目的，我可以在不更改任何其他代码的情况下为任何用户组运行它，并且当然可以很容易地从这些相同的表中适应DELETE，但对于75个左右的表来说是无法管理的我必须在用户和群组之间进行处理。

我遇到了this link on dynamic SQL，这种情绪非常密集，足以让我暂时吓跑......但我认为解决方案可能就在那里。

我非常熟悉JS和其他语言中的FOR()循环，这对于结构良好的数组来说是一块蛋糕，但显然它在SQL中并不那么简单（我还在学习，但是发现很多关于FOR和GOTO解决方案的负面评论......）。理想情况下，我有一个脚本查询查找具有特定列名的表，查询上面的每个表，然后向我吐出匹配列表，然后执行第二个类似的脚本来删除行。

任何人都可以帮我指出正确的方向吗？

Answer 1

好的，试试这个，有三个变量;列，colValue和预览。列应该是您正在检查相等的列（Group_ID），colValue您要查找的值（Unused_Group），预览应该是1以查看您将删除的内容，0应该删除它。

Declare @column     Nvarchar(256),
        @colValue   Nvarchar(256),
        @preview    Bit

Set     @column     = 'Group_ID'        
Set     @colValue   = 'Unused_Group'
Set     @preview    = 1 -- 1 = preview; 0 = delete

If      Object_ID('tempdb..#tables') Is Not Null Drop Table #tables
Create  Table #tables (tID Int, SchemaName Nvarchar(256), TableName Nvarchar(256))

--      Get all the tables with a column named [GROUP_ID]
Insert  #tables
Select  Row_Number() Over (Order By s.name, so.name), s.name, so.name
From    sysobjects so
Join    sys.schemas s
        On  so.uid = s.schema_id
Join    syscolumns sc
        On  so.id = sc.id
Where   so.xtype = 'u'
And     sc.name = @column

Select  *
From    #tables

Declare @SQL Nvarchar(Max),
        @schema Nvarchar(256),
        @table Nvarchar(256),
        @iter Int = 1

--      As long as there are tables to look at keep looping
While   Exists (Select  1
                From    #tables)
Begin
        --      Get the next table record to look at
        Select  @schema = SchemaName,
                @table = TableName
        From    #tables
        Where   tID = @iter

        --      If the table we're going to look at has dependencies on tables we have not 
        --      yet looked at move it to the end of the line and look at it after we look 
        --      at it's dependent tables (Handle foreign keys)
        If      Exists (Select  1
                        From    sysobjects o
                        Join    sys.schemas s1
                                On  o.uid = s1.schema_id
                        Join    sysforeignkeys fk
                                On  o.id = fk.rkeyid
                        Join    sysobjects o2
                                On  fk.fkeyid = o2.id
                        Join    sys.schemas s2
                                On  o2.uid = s2.schema_id
                        Join    #tables t
                                On  o2.name = t.TableName Collate Database_Default
                                And s2.name = t.SchemaName Collate Database_Default
                        Where   o.name = @table
                        And     s1.name = @schema)
        Begin
                --      Move the table to the end of the list to retry later
                Update  t
                Set     tID = (Select Max(tID) From #tables) + 1
                From    #tables t
                Where   tableName = @table
                And     schemaName = @schema

                --      Move on to the next table to look at
                Set     @iter = @iter + 1
        End
        Else
        Begin
                --      Delete the records we don't want anymore
                Set     @Sql =  Case
                                When    @preview = 1 
                                Then    'Select * ' -- If preview is 1 select from table
                                Else    'Delete t ' -- If preview is not 1 the delete from table
                                End +
                                'From    [' + @schema + '].[' + @table + '] t
                                Where   ' + @column + ' = ''' + @colValue + ''''

                Exec    sp_executeSQL @SQL;

                --      After we've done the work remove the table from our list
                Delete  t
                From    #tables t
                Where   tableName = @table
                And     schemaName = @schema

                --      Move on to the next table to look at
                Set     @iter = @iter + 1

        End
End

将其转换为存储过程只需将顶部的变量声明更改为sproc创建，这样就可以摆脱...

Declare @column     Nvarchar(256),
        @colValue   Nvarchar(256),
        @preview    Bit

Set     @column     = 'Group_ID'        
Set     @colValue   = 'Unused_Group'
Set     @preview    = 1 -- 1 = preview; 0 = delete
...

并将其替换为......

Create  Proc DeleteStuffFromManyTables (@column Nvarchar(256), @colValue Nvarchar(256), @preview Bit = 1)
As
...

你打电话给它......

Exec    DeleteStuffFromManyTable 'Group_ID', 'Unused_Group', 1

我评论了代码中的地狱，以帮助您了解它正在做什么;祝你好运！

Answer 2

您使用INFORMATION_SCHEMA个对象走在正确的轨道上。在查询编辑器中执行以下操作，它会为包含SELECT列DELETE值的表生成GROUP_ID和'Unused_Group'语句。

-- build select DML to manually review data that will be deleted
SELECT 'SELECT * FROM [' + TABLE_SCHEMA + '].[' + TABLE_NAME + '] WHERE [GROUP_ID] = ''Unused_Group'';'
FROM INFORMATION_SCHEMA.COLUMNS
WHERE COLUMN_NAME = 'GROUP_ID';

-- build delete DML to remove data
SELECT 'DELETE FROM [' + TABLE_SCHEMA + '].[' + TABLE_NAME + '] WHERE [GROUP_ID] = ''Unused_Group'';'
FROM INFORMATION_SCHEMA.COLUMNS
WHERE COLUMN_NAME = 'GROUP_ID';

由于这似乎是一次性清理工作，特别是因为您需要在数据被删除之前对其进行检查，所以我认为这不会使这个问题变得更加复杂。

Answer 3

如果可以，请考虑添加参照完整性并强制执行级联删除。在删除数据之前对数据进行可视化无济于事，但有助于控制孤立的行。

SQL：查询具有相同列名但具体值不同的许多表

3 个答案: