Merge multiple columns into one via a query in an access database

"Maybe this?

SELECT col1 FROM table
UNION
SELECT col2 FROM table
UNION
SELECT col3 FROM table
UNION
SELECT col4 FROM table

UNION only joins distinct values (if you have 4 't' values, it only puts one). UNION ALL will store duplicates."

"SELECT (Column1 + Column2 + Column3 + Column4)
FROM YourTable

The above will concatenate all four columns. If you need a space separator:

SELECT (Column1 + "" "" + Column2 + "" "" + Column3 + "" "" + Column4)
FROM YourTable

Thus the plus sign works as a concatenator. Finally, if you need to name the resulting column:

SELECT (Column1 + Column2 + Column3 + Column4) AS ColumnName
FROM YourTable

One last note, been ages since I last worked on Access, but I reckon you may also be able to concatenate fields with the || operator:

SELECT (Column1||Column2||Column3||Column4)
FROM YourTable

Following on the comments to this answer, different database engines may provide different syntaxes. An annoyance, no doubt:

SELECT Column1 & Column2 & Column3 & Column4
FROM YourTable

Here we replaced '+' with the usual '&' concatenation symbol present in many windows applications.

Cheers"