How to query and merge two rows of data in MySQL?

To combine two pieces of data into one query, you can use the UNION operator for merging them. For example:

SELECT column1, column2 FROM table1
UNION
SELECT column1, column2 FROM table2;

This will merge the data from table1 and table2 into one result set and return the data from column1 and column2. If duplicate data needs to be removed, the UNION ALL operator can be used.