我正在清理ERP,需要摆脱对未使用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!

我发现了这段整洁的代码花絮,以查找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'


通过结果,我可以在40多个表中搜索未使用的ID ...但这是很麻烦的。因此,我想自动执行此操作,并创建一个遍历所有这些表的查询,并删除在Unused_Group列中找到GROUP_ID的行。

在删除任何内容之前,我想可视化现有数据,因此我开始使用字符串连接构建类似的内容:

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


这对于我来说是可行的,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,并且当然很容易从这些相同的表中适应DELETE,但是对于我必须处理的75个左右的表却无法管理用户和组之间。

我遇到了this link on dynamic SQL,它的强度和密度足以吓我一跳……但我认为解决方案可能在某个地方。

我对JS和其他语言中的FOR()循环非常熟悉,这在结构良好的数组上简直是小菜一碟,但显然在SQL中并不是那么简单(我仍在学习,但发现了很多负面因素谈论可用的FOR和GOTO解决方案...)。理想情况下,我将拥有一个脚本来查询以查找具有特定列名的表,如上所述查询每个表,并向我吐出匹配项列表,然后执行第二个类似脚本以删除行。

谁能帮助我指出正确的方向?

最佳答案

好吧,尝试一下,有三个变量;列,colValue和预览。 Column应该是您要检查(Group_ID)是否相等的列,colValue您要查找的值(Unused_Group),并且Preview应该是1以查看将要删除的内容,而0应该将其删除。

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将只涉及将顶部的变量声明更改为sproc创建,因此您将摆脱...

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

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


并替换为...

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


然后用...来称呼它

Exec    DeleteStuffFromManyTable 'Group_ID', 'Unused_Group', 1


我用代码注释掉了地狱,以帮助您了解它的作用。祝好运!

关于sql - SQL:查询许多具有相同列名但结构不同的表以获取特定值,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/14820540/

10-12 07:20
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