The NULL specification identifies the character or a string of characters that BTEQ uses to represent null value fields in the reported results for a data-returning SQL request. The BTEQ NULL specification can range from 1 to 253 characters. The default value is a single question mark character.
Example – NULL
Use the following BTEQ NULL command, for example, to specify a string of three hyphens as the null specification:
.SET NULL AS '---'