>Use three part naming to include the name of the database, if the database is on the same instance
>
>

select Table1.fielda from Table1 
left join db2.dbo.Table2 on Table1.pk = Table2.pk 
where table2.field2 = '1234' -- assumming the schema is dbo and the database is db2 for table 2

Actually, the dbo can be omitted, it's the default. I frequently use db2..table syntax.