You can try correcting this UNION query by using a conversion function (ie: TO_CHAR function, TO_NUMBER function, or TO_DATE function) to convert the values to matching data types.
For example:
SELECT supplier_name
FROM orders
UNION
SELECT TO_CHAR(quantity)
FROM orders_audit;In this example, we've used the TO_CHAR function to convert the quantity column to a data type that is compatible with the supplier_name column.
亲测，奈斯。
