CMS: Find, in All Servers and Databases, if given Table.Column's data is unique

Using CMS, we can determine if all the Customer.CustomerID values are unique, and therefore, for example, a candidate for being made a primary key.

-- Find, in All Servers and Databases, if given Table.Column's data is unique. 
set nocount on

if left(convert(nvarchar, serverproperty('productversion')), 1) <> '8'
begin
    declare @Schema sysname     set @Schema = 'dba'
    declare @Table  sysname     set @Table  = 'Customer'
    declare @Column sysname     set @Column = 'CustomerId'

    declare @Sql nvarchar(4000)

    set @Sql = 'use [?]

                if  exists (select *
                              from sys.tables
                             where name = ''' + @Table + '''
                               and schema_id(''' + @Schema + ''') = schema_id)
                begin
                    declare @NonUniqueCount int
                    
                    select @NonUniqueCount = count(*)
                      from ' + @Schema + '.' + @Table  + '
                  group by ' + @Column + '
                    having count(*) > 1

                    if @NonUniqueCount is not null
                    begin
                        print @@SERVERNAME +'': '' + ''?'' + '' - @NonUniqueCount: '' + cast(@NonUniqueCount as nvarchar(50))
                    end
                end'

    exec sp_msforeachdb @Sql
end

CMS: Find all Databases on all Servers with Table "A" without Column "B"

This CMS (Central Management Server) code will tell you, for all databases in all servers, which tables of a given name don't have a column of a given name.

-- For all databases in all servers that have a "Customer" table, which ones don't have a "ZipCode" column? 
set nocount on

if left(convert(nvarchar, serverproperty('productversion')), 1) <> '8'
begin
    declare @Schema sysname     set @Schema = 'dbo'
    declare @Table  sysname     set @Table  = 'Customer'
    declare @Column sysname     set @Column = 'ZipCode'

    declare @Sql nvarchar(4000)

    set @Sql = 'use [?]

                if exists (select *
                            from sys.tables
                           where name = ''' + @Table + '''
                             and schema_id(''' + @Schema + ''') = schema_id)
                begin
                    if not exists (select *
                                     from sys.columns
                                    where name = ''' + @Column + '''
                                      and object_name(object_id) = ''' + @Table + ''')
                    begin
                        print @@SERVERNAME + '': '' + ''?'' + '' - ' + @Table + ' table has no ' + @Column + ' column''
                    end
                end'

    exec sp_msforeachdb @Sql
end

Quick Query to Display Database by Dataspace, Table, and Index

This query just breaks down the current database by dataspace, table, and index, giving you some useful information such as size in MB, pathname of the dataspace file, etc.

-- Shows size of each object in each dataspace in the current database. 
  select db_name()                              as DatabaseName
       , ds.name                                as DataSpaceName
       , ds.type_desc                           as DataSpaceTypeDesc
       , o.name                                 as TableName
       , i.name                                 as IndexName
       , i.type_desc                            as IndexDesc
       , (sum(ps.used_page_count) * 8) / 1024   as IndexSizeMB
       , df.physical_name                       as PathName
    from sys.objects                 o
    join sys.indexes                 i 
      on o.object_id = i.object_id 
    join sys.data_spaces             ds 
      on ds.data_space_id = i.data_space_id
    join sys.database_files          df
      on ds.data_space_id = df.data_space_id
    join sys.dm_db_partition_stats   ps
      on i.object_id = ps.object_id
group by ds.name
       , o.name
       , i.name
       , ds.type_desc
       , i.type_desc
       , df.physical_name
order by ds.name
       , o.name
       , i.name

Use Central Management Servers to Alter a Column in All Servers

The "Central Management Servers" functionality of SQL Server Management Studio is an excellent way to apply the same code to every server. By "every server", I mean groups of servers that you define: you might have different servers in folders named "Production", "Development", "QA", "SQL Server 2000", etc. It just depends on your needs.

To get to the "Central Management Servers" pane in SSMS, simply select the "View, Registered Servers" menu item. After you've set up your servers, you can execute queries against every database in every server. The example below changes the width of a column in a table. Note that in this example, we look for only databases whose name begins with "DB100", we exclude read-only databases, and we specify the schema, table, and column name we want to modify. The code also checks that the length isn't already set to the value we want, to avoid unnecessary noise in the output. This code is compatible with SQL Server 2000 and later (hence the use of "syscolumns", etc.)

-- Comment. 
set nocount on
declare @Sql nvarchar(4000)

set @Sql = 'use [?]

            if exists (select *
                         from syscolumns   sc
                         join sysobjects   so
                           on sc.id = so.id
                        where ''?''                                   like ''DB100%''
                          and databaseproperty(''?'', ''IsReadOnly'')    = 0
                          and user_name(so.uid)                          = ''dbo''
                          and object_name(sc.id)                         = ''Customer''
                          and sc.name                                    = ''FirstName''
                          and sc.length                                 != 120)
            begin
                select ''?'', sc.length
                  from syscolumns   sc
                  join sysobjects   so
                    on sc.id = so.id
                 where ''?''                                   like ''DB100%''
                   and databaseproperty(''?'', ''IsReadOnly'')    = 0
                   and user_name(so.uid)                          = ''dbo''
                   and object_name(sc.id)                         = ''Customer''
                   and sc.name                                    = ''FirstName''
                   and sc.length                                 != 120

                ALTER TABLE dbo.Customer ALTER COLUMN FirstName VARCHAR(120) NULL
            end '

exec sp_msforeachdb @Sql
go

References

For more information on Central Management Servers:

     Create a Central Management Server and Server Group

     Registered Servers and Central Management Server Stores

     Execute SQL Server query on multiple servers at the same time