sql - If an UNION doesn't contain the same column I can't use it? -


i read online:

each query in union must contain same columns, expressions, or aggregate functions, , must listed in same order.

if saying if have query example 

select   top (1) ties employee_id, sum(stars) 'total'     table_a group employee_id order 'total' desc

i can't use union different table_b name of employee table_a doesn't have. table_b share employee_id call differently emp_id , output name of employee table_b has emp_namefirst, emp_namelast.

what saying queries in union must produce result sets same schema. says absolutely nothing original source tables. long subqueries produce same number of columns same data types , in same order you're fine. point of union single result set there can 1 set of columns each subquery's result set must match that.

from you've described, union irrelevant you. union adds rows. want add columns. want join, not union.


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