Well, each select clause must have the same number of columns. The columns
from each table don't have to have the same names, but they must have
compatible data types. So for example if the second table contains a numeric
field that the first table doesn't, and the third table contains a text
field that the first and second tables don't, the UNION query might look
something like ...
SELECT FirstField, 0 AS SecondField, "" AS ThirdField FROM FirstTable
UNION SELECT FirstField, SecondField, "" AS ThirdField FROM SecondTable
UNION SELECT FirstField, SecondField, ThirdField FROM ThirdTable
BTW: The default behaviour of a UNION query is to include only unique
records - if a row from the second table exactly matches a row from the
first table, it will not be included. If you want to include duplicates, you
need to include the ALL predicate ...
SELECT etc FROM FirstTable
UNION ALL SELECT etc FROM SecondTable
--
Brendan Reynolds (MVP)
http://brenreyn.blogspot.com
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