Restore SQL Server 2012 backup to a SQL Server 2008 database?
You have couple of options :

Option A : Script out database in compatibility mode using Generate script option :

Note : If you script out database with schema and data, depending on your data size, the script will be massive and wont be handled by SSMS, sqlcmd or osql (might be in GB as well).



Option B: 

First script out tables first with all Indexes, FK's, etc and create blank tables in the destination database - option with SCHEMA ONLY (No data).

Use BCP to insert data


bcp out the data using below script. set SSMS in Text Mode and copy the output generated by below script in a bat file.

-- save below output in a bat file by executing below in SSMS in TEXT mode

-- clean up: create a bat file with this command --&gt; del D:\BCP\*.dat 

select '"C:\Program Files\Microsoft SQL Server\100\Tools\Binn\bcp.exe" ' /* path to BCP.exe */
    +  QUOTENAME(DB_NAME())+ '.' /* Current Database */
    +  QUOTENAME(SCHEMA_NAME(SCHEMA_ID))+'.'            
    +  QUOTENAME(name)  
    +  ' out D:\BCP\'  /* Path where BCP out files will be stored */
    +  REPLACE(SCHEMA_NAME(schema_id),' ','') + '_' 
    +  REPLACE(name,' ','') 
    + '.dat -T -E -SServerName\Instance -n' /* ServerName, -E will take care of Identity, -n is for Native Format */
from sys.tables
where is_ms_shipped = 0 and name &lt;&gt; 'sysdiagrams'                       /* sysdiagrams is classified my MS as UserTable and we dont want it */
/*and schema_name(schema_id) &lt;&gt; 'unwantedschema'    */                             /* Optional to exclude any schema  */
order by schema_name(schema_id)

Run the bat file that will generate the .dat files in the folder that you have specified.
Run below script on the destination server with SSMS in text mode again.

--- Execute this on the destination server.database from SSMS.

--- Make sure the change the @Destdbname and the bcp out path as per your environment.

declare @Destdbname sysname
set @Destdbname = 'destinationDB' /* Destination Database Name where you want to Bulk Insert in */
select 'BULK INSERT ' 
/*Remember Tables must be present on destination database */ 
+ QUOTENAME(@Destdbname) + '.' 
+ QUOTENAME(SCHEMA_NAME(SCHEMA_ID)) 
+ '.' + QUOTENAME(name) 
+ ' from ''D:\BCP\' /* Change here for bcp out path */ 
+ REPLACE(SCHEMA_NAME(schema_id), ' ', '') + '_' + REPLACE(name, ' ', '') 
+ '.dat'' with ( KEEPIDENTITY, DATAFILETYPE = ''native'', TABLOCK )' 
+ char(10) 
+ 'print ''Bulk insert for ' + REPLACE(SCHEMA_NAME(schema_id), ' ', '') + '_' + REPLACE(name, ' ', '') + ' is done... ''' 
+ char(10) + 'go'
   from sys.tables
   where is_ms_shipped = 0
and name &lt;&gt; 'sysdiagrams' /* sysdiagrams is classified my MS as UserTable and we dont want it */
and schema_name(schema_id) &lt;&gt; 'unwantedschema' /* Optional to exclude any schema */
    order by schema_name(schema_id) 

Run the output using SSMS to insert data back in the tables.


This is very fast bcp method as it uses Native mode.