Combining tables with same columns in SQL Server -

i trying combine 2 tables same columns in sql server.

individually, queries work fine:

select      _name, count(_name) occurrences      sp6815_nok      _value = 1 group      _name  order      occurrences desc 

and

select      _name, count(_name) occurrences      sp6814_nok      _value = 1 group      _name order      occurrences desc 

resulting in:

occurrences sp6815_nok

and

occurrences sp6814_nok

i need query perform exact filters listed in individual queries every time try 'join' clause or listing both tables under 'from' statement, ambiguous column error.

i think might because of messages or "_names" shared both tables, still need count occurrences , not overwrite them. help?

if need result in separated row use union

select _name,count(_name) occurrences sp6815_nok  _value = 1 group _name  union select _name,count(_name) sp6814_nok _value = 1 group _name order occurrences desc 

use union if want rows (also duplicated) use union if want distinct rows

otherwise if yoe want result on same row use qualified name

select sp6815_nok._name,count(sp6815_nok._name)   occurrences,  sp6814_nok._name,count(sp6814_nok._name) occurrences2 sp6815_nok  inner join sp6814_nok on sp6815_nok._value = sp6814_nok._value _value = 1 group sp6815_nok._name,  sp6814_nok._name order occurrences desc