A Symbol is a label or identifier that identifies a row in the Pattern and Result arguments. A Symbol can be any valid identifier (that is, a sequence of characters and digits that begins with a character) but is typically one or two uppercase letters. Symbols are case-insensitive; that is, 'SU' is identical to 'su', and the system reports an error if you use both.
For example, suppose that you have this input table:
This table has examples of symbol definitions and the rows of the table that they match in NONOVERLAPPING mode:
|Symbol Definition||Rows Matched|
|temp >= 80 AS H||1|
|winddirection = 'NW' AS NW||1, 4|
|winddirection = 'NW' OR windspeed > 12 AS W||1, 2, 4|
|cloudcover != 0.0 AND rh > 35 AS C||2, 3, 4
(An alternative to != is <>.)
|'true' AS A||1, 2, 3, 4
This symbol definition matches all rows, for any input table.
|city like 'tu%' AS TU||None
The like operator is case-sensitive. The % operator matches any number of characters.
|city not like 'tu%' AS TU||None|
|city ilike 'tu%' AS TU||1, 3, 4
The ilike operator is case-insensitive.
|city not ilike 'tu%' AS N||2|
|city ilike 'tu%n' as T||1, 3, 4
The % operator matches any number of characters.
|city ilike 'tu___n' as T||1, 3
The underscore (_) operator matches any single character. The pattern 'tu___n' has three underscores, so it matches 'Tucson' but not 'Tusayan'.
Rows with NULL values do not match any symbol. That is, the function ignores rows with missing values.