NULL Value

NULL is a reserved keyword used to indicate that a data value is unknown.

Be very careful when using NULL in expressions. NULL is not greater than, less than, equal to, or not equal to any other expression. Use the Boolean-Predicate for determining whether an expression value is NULL.

Notes

• Vertica stores data in projections, which are sorted in a specific way. All columns are stored in ASC (ascending) order. For columns of data type NUMERIC, INTEGER, DATE, TIME, TIMESTAMP, and INTERVAL, NULL values are placed at the beginning of sorted projections (NULLS FIRST), while for columns of data type FLOAT, STRING, and BOOLEAN, NULL values are placed at the end (NULLS LAST). For details, see NULL Sort Order and Runtime Sorting of NULL Values in Analytic Functions in Analyzing Data.
• Vertica also accepts NULL characters ('\0') in constant strings and no longer removes null characters from VARCHAR fields on input or output. NULL is the ASCII abbreviation for the NULL character.
• You can write queries with expressions that contain the <=> operator for NULL=NULL joins. See Equi-Joins and Non Equi-Joins in Analyzing Data.