class Sequel::SQL::StringExpression

Subclass of ComplexExpression where the expression results in a text/string/varchar value in SQL.

Constants

LIKE_MAP

Map of [regexp, case_insenstive] to ComplexExpression operator symbol

Public Class Methods

like(l, *ces) click to toggle source

Creates a SQL pattern match exprssion. left (l) is the SQL string we are matching against, and ces are the patterns we are matching. The match succeeds if any of the patterns match (SQL OR).

If a regular expression is used as a pattern, an SQL regular expression will be used, which is currently only supported on some databases. Be aware that SQL regular expression syntax is similar to ruby regular expression syntax, but it not exactly the same, especially for advanced regular expression features. Sequel just uses the source of the ruby regular expression verbatim as the SQL regular expression string.

If any other object is used as a regular expression, the SQL LIKE operator will be used, and should be supported by most databases.

The pattern match will be case insensitive if the last argument is a hash with a key of :case_insensitive that is not false or nil. Also, if a case insensitive regular expression is used (//i), that particular pattern which will always be case insensitive.

StringExpression.like(:a, 'a%') # ("a" LIKE 'a%' ESCAPE '\')
StringExpression.like(:a, 'a%', case_insensitive: true) # ("a" ILIKE 'a%' ESCAPE '\')
StringExpression.like(:a, 'a%', /^a/i) # (("a" LIKE 'a%' ESCAPE '\') OR ("a" ~* '^a'))
     # File lib/sequel/sql.rb
1768 def self.like(l, *ces)
1769   l, lre, lci = like_element(l)
1770   lci = (ces.last.is_a?(Hash) ? ces.pop : OPTS)[:case_insensitive] ? true : lci
1771   ces.map! do |ce|
1772     r, rre, rci = like_element(ce)
1773     BooleanExpression.new(LIKE_MAP[[lre||rre, lci||rci]], l, r)
1774   end
1775   ces.length == 1 ? ces[0] : BooleanExpression.new(:OR, *ces)
1776 end

Public Instance Methods

sql_string() click to toggle source

Return self instead of creating a new object to save on memory.

     # File lib/sequel/sql.rb
1792 def sql_string
1793   self
1794 end