Merging Column Output Using Concatenation

You can merge the display of columns using concatenation. This allows you to create more friendly and meaningful output. For example, in the customers table, the first_name and last_name columns contain the customer name. In the previous examples, these columns were selected and displayed independently. Wouldn’t it be nice to merge the display of those columns together under one column heading? You can do this using the concatenation operator (| |), as shown in the following example:

SELECT first_name || ' ' || last_name AS "Customer Name"
FROM customers;

Customer Name
--------------------
John Brown
Cynthia Green
Steve White
Gail Black
Doreen Blue