Convert Char to Int or vice versa

Question

I'm having trouble getting the right conversion without removing any values from the output.

I'd like to join two tables, but the primary key on one table is a char(4) and the other one has it as an INT .

Here is what I have done so far:

select A.ID,
B.ID from 
TableA A
 left join tableB B on
 cast(a.ID as varchar(4) = B.ID

I realized that this does not bring single digit values.

Table A values: 0,1,2,3,41
Table B values: 0,1,2,3,41

My output with my original query only gives me 41 and forgets about the other 4 values.

I need to be able to get the other 4 values

Any ideas on how I can get my desired out put?

Answer 1

I just tested this out using temp tables and it all works as expected (I did add a closing ) )

create table #tableA(id int)
insert #tablea (id) values (0), (1), (2), (3), (41)
create table #tableb(id char(4))
insert #tableb (id) values (0), (1), (2), (3), (41)

select A.ID,
B.ID from 
#TableA A
 left join #tableB B on
 cast(a.ID as varchar(4)) = B.ID

Answer 2

You can convert to strings:

select A.ID, B.ID
from  TableA A left join
      tableB B
      on cast(a.ID as varchar(4)) = B.ID;

As I've learned from painful experience, this does not handle leading zeros or 0 decimals. So 0.00 is not the same as 000 . However, this should be fine for single digits unless there is zero padding.

For numeric comparisons, go in the other direction

select A.ID, B.ID
from  TableA A left join
      tableB B
      on a.ID = try_convert(int, B.ID);

Of course, the real solution is to fix your tables so the columns have the same data type.