Francesco Francesco - 1 year ago 109
SQL Question

Simulate a left join without using "left join"

I need to simulate the left join effect without using the "left join" key.

I have two tables, A and B, both with

columns. I would like to select all the dbids on both tables, where the name in A equals the name in B.

I use this to make a synchronization, so at the beginning B is empty (so I will have couples with id from A with a value and id from B is null). Later I will have a mix of couples with value - value and value - null.

Normally it would be:

FROM A left join B
ON =

The problem is that I can't use the
left join
and wanted to know if/how it is possible to do the same thing.


you can use this approach, but you must be sure that the inner select only returns one row.

(select from B where = as B_ID