Use a select query result in an other query - sql

Question

Could please someone explain, how to use a result from a SELECT (1st select result)
Then use that result (1st select result) on a second query VALUES clause
there is an example (on Microsoft SQL Server) :
--1st query, select all DB1.client.name
select Name from DB1.client
--the result of that query is : 1st select result VALUES : ana,boby, ..., micky
--2nd query, compare DB1.client.name (1st select result) with DB2.client.name
--and get back who doesn't exist on second table
select v.Name
from (values
**(There i want use the result of my first query)**
) as v(Name)
where not exists (select *
from DB2.client c
where c.Name = v.Name);
--the result is ana, ..., micky
"..." mean some other results
i want compare first and second database to retrieve values which aren't in both databases

Answer 1

If you can, I recommend sub-query :
select Name
from DB1.client
where Name not in not exists (select name from DB2.client)
If you want reuse a query (not the result), see #Thkas answer.
It isn't possible to reuse the result in SQL Server, because SQL Server release the memory when the result is read. The trick is to insert the query's result in a temporary table, then you read this temporary table as many times as necessary :
--Insert into temporary table
insert into #tmpResult
select Name from DB1.client
--First read
select Name from #tmpResult
--Second read from sub-query
select Name
from #tmpResult
where Name not in not exists (select name from DB2.client)

Answer 2

According to your sample code I understood something like this. You can add two tables and do with WHERE the check you want.
select a.Name,b.Name
from DB1.client,
DB2.client as b
where a.Name != b.Name;
Also if you want to take as a result set from the first query:
Here I created a subquery which takes the results from the first query. You can correct me for columns.
with temp as (
select Name
from DB1.client
)select a.Name,b.Name
from temp as a ,
DB2.client as b
where a.Name != b.Name;