Sequel::SQL::StringExpression

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

Methods

Public Class

Public Instance

sql_string

Included modules

Constants

LIKE_MAP

{[true, true]=>:'~*', [true, false]=>:~, [false, true]=>:ILIKE, [false, false]=>:LIKE}.freeze

Map of [regexp, case_insenstive] to ComplexExpression operator symbol

Public Class methods

like(l, *ces)

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'))

[show source]

     # File lib/sequel/sql.rb
1777 def self.like(l, *ces)
1778   l, lre, lci = like_element(l)
1779   lci = (ces.last.is_a?(Hash) ? ces.pop : OPTS)[:case_insensitive] ? true : lci
1780   ces.map! do |ce|
1781     r, rre, rci = like_element(ce)
1782     BooleanExpression.new(LIKE_MAP[[lre||rre, lci||rci]], l, r)
1783   end
1784   ces.length == 1 ? ces[0] : BooleanExpression.new(:OR, *ces)
1785 end

Public Instance methods

sql_string()

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