CONCAT() — Concatenates two strings and returns the result.
CONCAT( string-expression, string-expression )
The CONCAT() function concatenates two strings and returns the resulting string. The string concatenation operator || performs the same function as CONCAT().
The following example concatenates the contents of two columns as part of a SELECT expression.
SELECT price, CONCAT(category,part_name) AS full_part_name FROM product_list ORDER BY price;
The next example does something similar but uses the || operator as a shorthand to concatenate three strings, two columns and a string constant, as part of a SELECT expression.
SELECT lastname || ', ' || firstname AS full_name FROM customers ORDER BY lastname, firstname;