Concatenation
The double vertical bar (||) is the preferred SQL concatenation operator. It can be used to concatenate two numbers, two character strings, or a number and a character string.
The underscore (_) is provided as an SQL concatenation operator for ObjectScript compatibility. This concatenation operator can only be used to concatenate two character strings.
If the two operands are both character strings, and both strings have the same collation type, the resulting concatenated string has that collation type. In all other cases, the result of concatenation is of collation type EXACT.
