The used SELECT statements have a different number of columns

Question

For examples I don\'t know how many rows in each table are and I try to do like this:

SELECT * FROM members 
UNION 
SELECT * FROM inventory

Answer 1

I don't know how many rows in each table

Are you sure this isn't what you want?

SELECT 'members' AS TableName, Count(*) AS Cnt FROM members 
UNION ALL
SELECT 'inventory', Count(*) FROM inventory