Set READ UNCOMMITED for a query with a table join (Ver 12.5. and 15.5)

Question

Hi all,
this is an example of how to set the READ UNCOMMITED isolation level for a simple query:
select col_a from mytable at isolation 0
What about a query with an equi-join?
Is it:
select col_a
from mytable t1, mytable t2
at isolation 0
I am sorry for the simple question, I did not find a auitable example in the documentation.
Best Regards
Arthur

Answer 1

Yeah, the docs aren't very good at providing a robust set of examples so you've gotta:
1 - review the command syntax and then
2 - try a few examples until you find the format that works
1 - From the ASE 15.5 Commands reference manual we find the following syntax:
=========================
select ::=
          select [all | distinct]
          [top unsigned_integer]
          select_list
          [into_clause]
          [from_clause]
          [where_clause]
          [group_by_clause]
          [having_clause]
          [order_by_clause]
          [compute_clause]
          [read_only_clause]
          [isolation_clause]
          [browse_clause]
          [plan_clause]
=========================
This shows us that the isolation clause is attached at the 'end' of the query as a query-level specifier (along with the 'group by', 'order by' and 'having' clauses).
From this syntax I'd say your proposed query looks correct so ...
2 - Try running your example to see if you get a syntax error ("When in doubt, try it out!"), eg:
=========================
select s.name,c.name
from sysobjects s, syscolumns c
where s.id = c.id
at isolation 0
go
name
sysobjects
sysobjects
sysobjects
... snip ...
=========================