ploticus: lists

## lists | Welcome Gallery Handbook |
| Manual page for lists(PL)

## Comma-delimited lists

A comma-delimited list (or "list" for short) is a list of items, delimited with commas. A list is stored as a single alphanumeric variable or field.`` Individual members cannot contain embedded commas. Embedded whitespace is allowed within or outside of individual list members (the list may need to be quoted).``

An example: `Harry,Ron,Hermione`

Lists are most suitable where individual values are known to be small in size (such as controlled-vocabulary tags or integer id numbers) and where it is known that there will not be a huge number of choices. The total length of a comma-delimited list is limited to 250 characters.``

Lists allow a set of values to be manipulated as a unit, which is often convenient. They can be used with conditional expression and WHERE clause operators such as `IN`, `INRANGE`, and `CONTAINS`. Some functions also work with lists.``

In midriff, lists are a convenient way to store responses entered from `<SELECT MULTIPLE>` boxes on CGI forms. The #optionlist directive allows <SELECT MULTIPLE> boxes to be initialized directly by a list.`` When a form is submitted <SELECT MULTIPLE> responses can be converted to a list in the form target page using the #cgilistvar directive.``

In shsql database applications, lists can often be used to represent shallow one-to-many or many-to-many relationships without having to resort to a separate relation table. Since lists contain a vector of information they cannot be involved in `JOIN`s.`` If `JOIN`s are not required, use of lists can simplify design and code.``
data display engine
Copyright Steve Grubb

Markup created by unroff 1.0, `` `` December 10, 2002.