The following example shows an expression that concatenates employee first names and employee last names from two columns. This expression removes the spaces from the end of the first name and the beginning of the last name, concatenates a space to the end of each first name, then concatenates the last name:
LTRIM( RTRIM( EMP_FIRST ) || ' ' || LTRIM( EMP_LAST ))
You can also use the CONCAT function to concatenate two string values. The || operator, however, produces the same results in less time.