Rewrite query using cursor (perhaps with a join) in SQL Server

Question

I have a query (not written myself) and I am trying to make it run faster. I have seem this SQL Query with Cursor optimization

Cannot see if the answer applies for my case. Is it possible to rewrite this query?

The structure is:

TRUNCATE TABLE TableA

declare @myvar as varchar(255)


declare cur CURSOR LOCAL FAST_FORWARD
for SELECT SUB_TRANS
    FROM TableB
open cur

fetch next from cur 
into @myvar

while @@FETCH_STATUS = 0 
BEGIN

    INSERT INTO TableA
    SELECT many_thing
    from 4_tables_with_join(Note: @myvar is included as a join condition)



    fetch next from cur 
    into @myvar

END

close cur
deallocate cur

Answer 1

As a "general hint": you most likely don't need the cursor logic at all. I would recommend rewriting this as a straight insert ... select query.

As pseudo-code, this would look like:

insert into tablea (col1, col2, ...)
select many_thing
from tableb tb
inner join ... -- use "tb.subtrans" here in the join conditions instead of "@myvar"