SQL - Joining tables witout a common key

It is always best to allow a remote database to handle as much work as possible and return as little data as possible over the network. SQL is a very universal language used by most, if not all database systems.

Recently I had occasion to extract data from SQL Server and found it most efficient to utilize its system tables to do just that. In my case, I wanted both the total record count as well as the number of character and numeric data types. While this information is available using SAS dictionary tables from an ODBC libname statement, it was taking up to four minutes to return the data.

The code below creates two derived tables that contain the desired information. The problem was that there is not a common key to perform the required join. While a cross-join is possible, those joins in PROC SQL write a WARNING to the SAS log which is not allowed in my parselog macro.

The solution was to join the derived table using the ON 1 = 1 syntax. This worked and returned the correct answer in under one second which is much faster than the four minutes using a libname.

proc sql;
   connect to odbc(dsn=mydsn authdomain="myauth");
      create table results as
         select        totalrows
                     , char_cnt
                     , num_cnt
         from connection to odbc(
            select     cnt.totalrows
                     , col.char_cnt
                     , col.num_cnt
            from
            ( select   sum(p.rows) as totalrows                   
              from     sys.tables t
              join     sys.partitions p
                on         t.object_id = p.object_id
                       and p.index_id IN (0, 1)
              where    t.name = 'balancechanges' 
            ) as cnt
            join
            ( select   
                       sum(iif(ty.name in('nvarchar', 'varchar', 'char'
                                        , 'nchar', 'text'), 1, 0)) as char_cnt
                     , sum(iif(ty.name in('nvarchar', 'varchar', 'char'
                                        , 'nchar', 'text'), 0, 1)) as num_cnt
              from     sys.tables t
              join     sys.columns c
                on     t.object_id = c.object_id
              join     sys.types ty
                on     c.user_type_id = ty.user_type_id
              where    t.name = 'balancechanges'
            ) as col
              on       1 = 1 
       );
   disconnect from odbc;
quit;