Question

I need to ask something is there any way combine two tables different count of columns like:

Select a,b,c, from x

 union 

Select d, e from y

Answer 1

you need to do something like this

Select a,b,c from x

 union all  -- ALL doesn't filter dups and is faster

Select d, e, '' as f from y

I used ” but you might want to use NULL or 0, NULL will be compatible will all data types, ” will not be

I also used UNION ALL not UNION since it will perform better because it doesn’t have to do a sort operation to get rid of dups

the alias f is not needed here either because the top query determines the name of the columns in the resultset